other / mew-iview

  <template>

      <div

          :class="classes"

          v-click-outside.capture="onClickOutside"

          v-click-outside:mousedown.capture="onClickOutside"

          v-click-outside:touchstart.capture="onClickOutside"

      >

          <div

              ref="reference"

  
              :class="selectionCls"
              :tabindex="selectTabindex"
  
              @blur="toggleHeaderFocus"
              @focus="toggleHeaderFocus"
  
              @click="toggleMenu"
              @keydown.esc="handleKeydown"
              @keydown.enter="handleKeydown"

              @keydown.up.prevent="handleKeydown"
              @keydown.down.prevent="handleKeydown"

              @keydown.tab="handleKeydown"
              @keydown.delete="handleKeydown"
  
  
              @mouseenter="hasMouseHoverHead = true"
              @mouseleave="hasMouseHoverHead = false"
  
          >

              <slot name="input">

                  <input type="hidden" :name="name" :value="publicValue">
                  <select-head
                      :filterable="filterable"
                      :multiple="multiple"
                      :values="values"
                      :clearable="canBeCleared"

                      :prefix="prefix"

                      :disabled="disabled"

                      :remote="remote"
                      :input-element-id="elementId"
                      :initial-label="initialLabel"
                      :placeholder="placeholder"
                      :query-prop="query"

                      :max-tag-count="maxTagCount"
                      :max-tag-placeholder="maxTagPlaceholder"

  
                      @on-query-change="onQueryChange"
                      @on-input-focus="isFocused = true"
                      @on-input-blur="isFocused = false"

                      @on-clear="clearSingleSelect"

                  >
                      <slot name="prefix" slot="prefix"></slot>
                  </select-head>

              </slot>

          </div>

          <transition name="transition-drop">

              <Drop

                  :class="dropdownCls"

                  v-show="dropVisible"
                  :placement="placement"
                  ref="dropdown"
                  :data-transfer="transfer"

                  :transfer="transfer"

                  v-transfer-dom
              >
                  <ul v-show="showNotFoundLabel" :class="[prefixCls + '-not-found']"><li>{{ localeNotFoundText }}</li></ul>
                  <ul :class="prefixCls + '-dropdown-list'">

                      <functional-options
                          v-if="(!remote) || (remote && !loading)"
                          :options="selectOptions"
                          :slot-update-hook="updateSlotOptions"
                          :slot-options="slotOptions"
                      ></functional-options>

                  </ul>

                  <ul v-show="loading" :class="[prefixCls + '-loading']">{{ localeLoadingText }}</ul>

              </Drop>
          </transition>

      </div>
  </template>
  <script>

      import Drop from './dropdown.vue';

      import {directive as clickOutside} from 'v-click-outside-x';

      import TransferDom from '../../directives/transfer-dom';

      import { oneOf } from '../../utils/assist';

      import Emitter from '../../mixins/emitter';

      import Locale from '../../mixins/locale';

      import SelectHead from './select-head.vue';
      import FunctionalOptions from './functional-options.vue';

  
      const prefixCls = 'ivu-select';

      const optionRegexp = /^i-option$|^Option$/i;

      const optionGroupRegexp = /option-?group/i;

  
      const findChild = (instance, checkFn) => {
          let match = checkFn(instance);
          if (match) return instance;
          for (let i = 0, l = instance.$children.length; i < l; i++){
              const child = instance.$children[i];
              match = findChild(child, checkFn);
              if (match) return match;
          }
      };

      const findOptionsInVNode = (node) => {
          const opts = node.componentOptions;

          if (opts && opts.tag.match(optionRegexp)) return [node];

          if (!node.children && (!opts || !opts.children)) return [];

          const children = [...(node.children || []), ...(opts && opts.children || [])];

          const options = children.reduce(

              (arr, el) => [...arr, ...findOptionsInVNode(el)], []
          ).filter(Boolean);
          return options.length > 0 ? options : [];
      };
  
      const extractOptions = (options) => options.reduce((options, slotEntry) => {
          return options.concat(findOptionsInVNode(slotEntry));
      }, []);
  

      const applyProp = (node, propName, value) => {
          return {
              ...node,
              componentOptions: {
                  ...node.componentOptions,
                  propsData: {
                      ...node.componentOptions.propsData,
                      [propName]: value,
                  }
              }
          };
      };
  

      const getNestedProperty = (obj, path) => {
          const keys = path.split('.');
          return keys.reduce((o, key) => o && o[key] || null, obj);
      };
  
      const getOptionLabel = option => {

          if (option.componentOptions.propsData.label) return option.componentOptions.propsData.label;

          const textContent = (option.componentOptions.children || []).reduce((str, child) => str + (child.text || ''), '');
          const innerHTML = getNestedProperty(option, 'data.domProps.innerHTML');

          return textContent || (typeof innerHTML === 'string' ? innerHTML : '');

      };
  

      const checkValuesNotEqual = (value,publicValue,values) => {
          const strValue = JSON.stringify(value);
          const strPublic = JSON.stringify(publicValue);
          const strValues = JSON.stringify(values.map( item => {
              return item.value;
          }));
          return strValue !== strPublic || strValue !== strValues || strValues !== strPublic;
      };
  

      const ANIMATION_TIMEOUT = 300;
  

      export default {

          name: 'iSelect',

          mixins: [ Emitter, Locale ],

          components: { FunctionalOptions, Drop, SelectHead },

          directives: { clickOutside, TransferDom },

          props: {

              value: {

                  type: [String, Number, Array],
                  default: ''
              },

              // 使用时，也得设置 value 才行

              label: {
                  type: [String, Number, Array],
                  default: ''
              },

              multiple: {
                  type: Boolean,
                  default: false
              },
              disabled: {
                  type: Boolean,
                  default: false
              },
              clearable: {
                  type: Boolean,
                  default: false
              },
              placeholder: {

                  type: String

              },
              filterable: {
                  type: Boolean,
                  default: false
              },
              filterMethod: {
                  type: Function
              },

              remoteMethod: {
                  type: Function
              },
              loading: {
                  type: Boolean,
                  default: false
              },
              loadingText: {
                  type: String
              },

              size: {
                  validator (value) {

                      return oneOf(value, ['small', 'large', 'default']);

                  },
                  default () {

                      return !this.$IVIEW || this.$IVIEW.size === '' ? 'default' : this.$IVIEW.size;

                  }
              },
              labelInValue: {
                  type: Boolean,
                  default: false

              },
              notFoundText: {

                  type: String

              },
              placement: {
                  validator (value) {

                      return oneOf(value, ['top', 'bottom', 'top-start', 'bottom-start', 'top-end', 'bottom-end']);

                  },

                  default: 'bottom-start'

              },
              transfer: {
                  type: Boolean,

                  default () {

                      return !this.$IVIEW || this.$IVIEW.transfer === '' ? false : this.$IVIEW.transfer;

                  }

              },
              // Use for AutoComplete
              autoComplete: {
                  type: Boolean,
                  default: false

              },
              name: {
                  type: String

              },
              elementId: {
                  type: String

              },
              transferClassName: {
                  type: String
              },

              // 3.4.0

              prefix: {
                  type: String
              },

              // 3.4.0
              maxTagCount: {
                  type: Number
              },
              // 3.4.0
              maxTagPlaceholder: {

                  type: Function

              }

          },

          mounted(){
              this.$on('on-select-selected', this.onOptionClick);
  
              // set the initial values if there are any

              if (!this.remote && this.selectOptions.length > 0){
                  this.values = this.getInitialValue().map(value => {
                      if (typeof value !== 'number' && !value) return null;
                      return this.getOptionData(value);
                  }).filter(Boolean);

              }

              this.checkUpdateStatus();

          },

          data () {

              return {
                  prefixCls: prefixCls,

                  values: [],

                  dropDownWidth: 0,

                  visible: false,

                  focusIndex: -1,
                  isFocused: false,

                  query: '',

                  initialLabel: this.label,
                  hasMouseHoverHead: false,
                  slotOptions: this.$slots.default,
                  caretPosition: -1,
                  lastRemoteQuery: '',

                  unchangedQuery: true,

                  hasExpectedValue: false,

                  preventRemoteCall: false,

                  filterQueryChange: false,  // #4273

              };

          },
          computed: {
              classes () {
                  return [

                      `${prefixCls}`,

                      {

                          [`${prefixCls}-visible`]: this.visible,
                          [`${prefixCls}-disabled`]: this.disabled,
                          [`${prefixCls}-multiple`]: this.multiple,
                          [`${prefixCls}-single`]: !this.multiple,
                          [`${prefixCls}-show-clear`]: this.showCloseIcon,
                          [`${prefixCls}-${this.size}`]: !!this.size

                      }

                  ];

              },

              dropdownCls () {
                  return {
                      [prefixCls + '-dropdown-transfer']: this.transfer,

                      [prefixCls + '-multiple']: this.multiple && this.transfer,
                      ['ivu-auto-complete']: this.autoComplete,

                      [this.transferClassName]: this.transferClassName

                  };
              },
              selectionCls () {
                  return {

                      [`${prefixCls}-selection`]: !this.autoComplete,
                      [`${prefixCls}-selection-focused`]: this.isFocused

                  };
              },

              localeNotFoundText () {

                  if (typeof this.notFoundText === 'undefined') {

                      return this.t('i.select.noMatch');
                  } else {
                      return this.notFoundText;
                  }

              },

              localeLoadingText () {

                  if (typeof this.loadingText === 'undefined') {

                      return this.t('i.select.loading');
                  } else {
                      return this.loadingText;
                  }
              },

              transitionName () {
                  return this.placement === 'bottom' ? 'slide-up' : 'slide-down';

              },
              dropVisible () {
                  let status = true;

                  const noOptions = !this.selectOptions || this.selectOptions.length === 0;
                  if (!this.loading && this.remote && this.query === '' && noOptions) status = false;

                  if (this.autoComplete && noOptions) status = false;

                  return this.visible && status;

              },

              showNotFoundLabel () {
                  const {loading, remote, selectOptions} = this;

                  return selectOptions && selectOptions.length === 0 && (!remote || (remote && !loading));

              },

              publicValue(){

                  // 改变 labelInValue 实现，解决 bug:Select，label-in-value时，搜索、多选，先选一个，再选第二个，会替代第一个
                  // if (this.labelInValue){
                  //     return this.multiple ? this.values : this.values[0];
                  // } else {
                  //     return this.multiple ? this.values.map(option => option.value) : (this.values[0] || {}).value;
                  // }

                      return this.multiple ? this.values.map(option => option.value) : (this.values[0] || {}).value;

              },

              canBeCleared(){
                  const uiStateMatch = this.hasMouseHoverHead || this.active;

                  const qualifiesForClear = !this.multiple && !this.disabled && this.clearable;

                  return uiStateMatch && qualifiesForClear && this.reset; // we return a function
              },
              selectOptions() {
                  const selectOptions = [];

                  const slotOptions = (this.slotOptions || []);

                  let optionCounter = -1;
                  const currentIndex = this.focusIndex;

                  const selectedValues = this.values.filter(Boolean).map(({value}) => value);

                  if (this.autoComplete) {
                      const copyChildren = (node, fn) => {
                          return {
                              ...node,
                              children: (node.children || []).map(fn).map(child => copyChildren(child, fn))
                          };
                      };
                      const autoCompleteOptions = extractOptions(slotOptions);
                      const selectedSlotOption = autoCompleteOptions[currentIndex];
  

                      return slotOptions.map(node => {

                          if (node === selectedSlotOption || getNestedProperty(node, 'componentOptions.propsData.value') === this.value) return applyProp(node, 'isFocused', true);

                          return copyChildren(node, (child) => {
                              if (child !== selectedSlotOption) return child;
                              return applyProp(child, 'isFocused', true);
                          });
                      });

                  }

                  for (let option of slotOptions) {

                      const cOptions = option.componentOptions;
                      if (!cOptions) continue;

                      if (cOptions.tag.match(optionGroupRegexp)){
                          let children = cOptions.children;

                          // remove filtered children
                          if (this.filterable){
                              children = children.filter(
                                  ({componentOptions}) => this.validateOption(componentOptions)
                              );
                          }

                          // fix #4371
                          children = children.map(opt => {

                              optionCounter = optionCounter + 1;
                              return this.processOption(opt, selectedValues, optionCounter === currentIndex);
                          });

                          // keep the group if it still has children  // fix #4371
                          if (children.length > 0) selectOptions.push({...option,componentOptions:{...cOptions,children:children}});

                      } else {
                          // ignore option if not passing filter

                          if (this.filterQueryChange) {

                              const optionPassesFilter = this.filterable ? this.validateOption(cOptions) : option;
                              if (!optionPassesFilter) continue;
                          }

                          optionCounter = optionCounter + 1;

                          selectOptions.push(this.processOption(option, selectedValues, optionCounter === currentIndex));

                      }

                  }
  

                  return selectOptions;

              },

              flatOptions(){

                  return extractOptions(this.selectOptions);

              },
              selectTabindex(){
                  return this.disabled || this.filterable ? -1 : 0;
              },
              remote(){
                  return typeof this.remoteMethod === 'function';
              }
          },
          methods: {
              setQuery(query){ // PUBLIC API
                  if (query) {
                      this.onQueryChange(query);
                      return;
                  }
                  if (query === null) {
                      this.onQueryChange('');
                      this.values = [];

                      // #5620,修复清空搜索关键词后，重新搜索相同的关键词没有触发远程搜索
                      this.lastRemoteQuery = '';

                  }
              },

              clearSingleSelect(){ // PUBLIC API

                  // fix #446
                  if (!this.multiple) this.$emit('input', '');

                  this.$emit('on-clear');

                  this.hideMenu();

                  if (this.clearable) this.reset();

              },
              getOptionData(value){
                  const option = this.flatOptions.find(({componentOptions}) => componentOptions.propsData.value === value);

                  if (!option) return null;

                  const label = getOptionLabel(option);

                  // 修复多选时，选项有disabled属性，选中项仍然能删除的 bug
                  const disabled = option.componentOptions.propsData.disabled;

                  return {
                      value: value,
                      label: label,

                      disabled: disabled

                  };
              },
              getInitialValue(){

                  const {multiple, remote, value} = this;

                  let initialValue = Array.isArray(value) ? value : [value];

                  if (!multiple && (typeof initialValue[0] === 'undefined' || (String(initialValue[0]).trim() === '' && !Number.isFinite(initialValue[0])))) initialValue = [];

                  if (remote && !multiple && value) {
                      const data = this.getOptionData(value);
                      this.query = data ? data.label : String(value);
                  }

                  return initialValue.filter((item) => {

                      return Boolean(item) || item === 0;

                  });

              },
              processOption(option, values, isFocused){
                  if (!option.componentOptions) return option;
                  const optionValue = option.componentOptions.propsData.value;
                  const disabled = option.componentOptions.propsData.disabled;
                  const isSelected = values.includes(optionValue);
  
                  const propsData = {
                      ...option.componentOptions.propsData,
                      selected: isSelected,
                      isFocused: isFocused,
                      disabled: typeof disabled === 'undefined' ? false : disabled !== false,
                  };

                  return {
                      ...option,
                      componentOptions: {
                          ...option.componentOptions,
                          propsData: propsData

                      }

                  };
              },

              validateOption({children, elm, propsData}){

                  const value = propsData.value;
                  const label = propsData.label || '';

                  const textContent = (elm && elm.textContent) || (children || []).reduce((str, node) => {
                      const nodeText = node.elm ? node.elm.textContent : node.text;
                      return `${str} ${nodeText}`;
                  }, '') || '';

                  const stringValues = JSON.stringify([value, label, textContent]);

                  const query = this.query.toLowerCase().trim();

                  return stringValues.toLowerCase().includes(query);

              },

              toggleMenu (e, force) {

                  if (this.disabled) {

                      return false;

                  }

                  this.visible = typeof force !== 'undefined' ? force : !this.visible;
                  if (this.visible){
                      this.dropDownWidth = this.$el.getBoundingClientRect().width;

                      this.broadcast('Drop', 'on-update-popper');

                  }

              },

              hideMenu () {
                  this.toggleMenu(null, false);

                  setTimeout(() => this.unchangedQuery = true, ANIMATION_TIMEOUT);

              },

              onClickOutside(event){
                  if (this.visible) {

                      if (event.type === 'mousedown') {
                          event.preventDefault();
                          return;
                      }

                      if (this.transfer) {
                          const {$el} = this.$refs.dropdown;
                          if ($el === event.target || $el.contains(event.target)) {
                              return;
                          }
                      }
  
  

                      if (this.filterable) {

                          const input = this.$el.querySelector('input[type="text"]');

                          this.caretPosition = input.selectionStart;
                          this.$nextTick(() => {
                              const caretPosition = this.caretPosition === -1 ? input.value.length : this.caretPosition;
                              input.setSelectionRange(caretPosition, caretPosition);

                          });
                      }
  

                      if (!this.autoComplete) event.stopPropagation();

                      event.preventDefault();
                      this.hideMenu();
                      this.isFocused = true;
                  } else {
                      this.caretPosition = -1;
                      this.isFocused = false;

                  }
              },

              reset(){

                  this.query = '';
                  this.focusIndex = -1;

                  this.unchangedQuery = true;

                  this.values = [];

                  this.filterQueryChange = false;

              },
              handleKeydown (e) {

                  if (e.key === 'Backspace'){
                      return; // so we don't call preventDefault
                  }
  

                  if (this.visible) {

                      e.preventDefault();
                      if (e.key === 'Tab'){
                          e.stopPropagation();
                      }
  

                      // Esc slide-up

                      if (e.key === 'Escape') {

                          e.stopPropagation();

                          this.hideMenu();
                      }
                      // next

                      if (e.key === 'ArrowUp') {
                          this.navigateOptions(-1);

                      }
                      // prev

                      if (e.key === 'ArrowDown') {
                          this.navigateOptions(1);

                      }
                      // enter

                      if (e.key === 'Enter') {
                          if (this.focusIndex === -1) return this.hideMenu();

                          const optionComponent = this.flatOptions[this.focusIndex];

  
                          // fix a script error when searching
                          if (optionComponent) {
                              const option = this.getOptionData(optionComponent.componentOptions.propsData.value);
                              this.onOptionClick(option);
                          } else {
                              this.hideMenu();
                          }

                      }

                  } else {
                      const keysThatCanOpenSelect = ['ArrowUp', 'ArrowDown'];
                      if (keysThatCanOpenSelect.includes(e.key)) this.toggleMenu(null, true);

                  }
  

              },
              navigateOptions(direction){
                  const optionsLength = this.flatOptions.length - 1;

                  let index = this.focusIndex + direction;
                  if (index < 0) index = optionsLength;
                  if (index > optionsLength) index = 0;

                  // find nearest option in case of disabled options in between
                  if (direction > 0){
                      let nearestActiveOption = -1;
                      for (let i = 0; i < this.flatOptions.length; i++){
                          const optionIsActive = !this.flatOptions[i].componentOptions.propsData.disabled;
                          if (optionIsActive) nearestActiveOption = i;
                          if (nearestActiveOption >= index) break;

                      }

                      index = nearestActiveOption;
                  } else {
                      let nearestActiveOption = this.flatOptions.length;
                      for (let i = optionsLength; i >= 0; i--){
                          const optionIsActive = !this.flatOptions[i].componentOptions.propsData.disabled;
                          if (optionIsActive) nearestActiveOption = i;
                          if (nearestActiveOption <= index) break;

                      }

                      index = nearestActiveOption;

                  }

                  this.focusIndex = index;

              },

              onOptionClick(option) {
                  if (this.multiple){
  
                      // keep the query for remote select
                      if (this.remote) this.lastRemoteQuery = this.lastRemoteQuery || this.query;
                      else this.lastRemoteQuery = '';

                      const valueIsSelected = this.values.find(({value}) => value === option.value);
                      if (valueIsSelected){
                          this.values = this.values.filter(({value}) => value !== option.value);

                      } else {

                          this.values = this.values.concat(option);

                      }

  
                      this.isFocused = true; // so we put back focus after clicking with mouse on option elements
                  } else {

                      this.query = String(option.label).trim();

                      this.values = [option];
                      this.lastRemoteQuery = '';
                      this.hideMenu();
                  }
  

                  this.focusIndex = this.flatOptions.findIndex((opt) => {
                      if (!opt || !opt.componentOptions) return false;
                      return opt.componentOptions.propsData.value === option.value;
                  });
  

                  if (this.filterable){

                      const inputField = this.$el.querySelector('input[type="text"]');
                      if (!this.autoComplete) this.$nextTick(() => inputField.focus());

                  }

                  this.broadcast('Drop', 'on-update-popper');

                  setTimeout(() => {

                      this.filterQueryChange = false;
                  }, ANIMATION_TIMEOUT);

              },

              onQueryChange(query) {

                  if (query.length > 0 && query !== this.query) {
                    // in 'AutoComplete', when set an initial value asynchronously,
                    // the 'dropdown list' should be stay hidden.
                    // [issue #5150]

                      if (this.autoComplete) {
                          let isInputFocused =
                              document.hasFocus &&
                              document.hasFocus() &&
                              document.activeElement === this.$el.querySelector('input');
                          this.visible = isInputFocused;
                      } else {
                          this.visible = true;
                      }

                  }
  

                  this.query = query;

                  this.unchangedQuery = this.visible;

                  this.filterQueryChange = true;

              },

              toggleHeaderFocus({type}){
                  if (this.disabled) {
                      return;

                  }

                  this.isFocused = type === 'focus';

              },

              updateSlotOptions(){
                  this.slotOptions = this.$slots.default;

              },
              checkUpdateStatus() {
                  if (this.getInitialValue().length > 0 && this.selectOptions.length === 0) {
                      this.hasExpectedValue = true;
                  }

              },

          },

          watch: {

              value(value){

                  const {getInitialValue, getOptionData, publicValue, values} = this;

                  this.checkUpdateStatus();

                  if (value === '') this.values = [];

                  else if (checkValuesNotEqual(value,publicValue,values)) {

                      this.$nextTick(() => this.values = getInitialValue().map(getOptionData).filter(Boolean));

                      if (!this.multiple) this.dispatch('FormItem', 'on-form-change', this.publicValue);

                  }

              },
              values(now, before){
                  const newValue = JSON.stringify(now);
                  const oldValue = JSON.stringify(before);

                  // v-model is always just the value, event with labelInValue === true

                  // const vModelValue = (this.publicValue && this.labelInValue === false) ?
                  //     (this.multiple ? this.publicValue.map(({value}) => value) : this.publicValue.value) :
                  //     this.publicValue;
                  // 改变 labelInValue 的实现：直接在 emit 时改数据
                  let vModelValue = this.publicValue;

                  const shouldEmitInput = newValue !== oldValue && vModelValue !== this.value;

                  if (shouldEmitInput) {

                      let emitValue = this.publicValue;
                      if (this.labelInValue) {
                          if (this.multiple) {
                              emitValue = this.values;
                          } else {
                              emitValue = this.values[0];
                          }
                      }
  
                      // Form 重置时，如果初始值是 null，也置为 null，而不是 []
                      if (Array.isArray(vModelValue) && !vModelValue.length && this.value === null) vModelValue = null;
                      else if (vModelValue === undefined && this.value === null) vModelValue = null;
  

                      this.$emit('input', vModelValue); // to update v-model

                      this.$emit('on-change', emitValue);
                      this.dispatch('FormItem', 'on-form-change', emitValue);

                  }

              },

              query (query) {
                  this.$emit('on-query-change', query);
                  const {remoteMethod, lastRemoteQuery} = this;
                  const hasValidQuery = query !== '' && (query !== lastRemoteQuery || !lastRemoteQuery);

                  const shouldCallRemoteMethod = remoteMethod && hasValidQuery && !this.preventRemoteCall;
                  this.preventRemoteCall = false; // remove the flag

  
                  if (shouldCallRemoteMethod){
                      this.focusIndex = -1;
                      const promise = this.remoteMethod(query);
                      this.initialLabel = '';
                      if (promise && promise.then){
                          promise.then(options => {
                              if (options) this.options = options;
                          });

                      }

                  }

                  if (query !== '' && this.remote) this.lastRemoteQuery = query;

              },

              loading(state){
                  if (state === false){
                      this.updateSlotOptions();
                  }
              },
              isFocused(focused){

                  const el = this.filterable ? this.$el.querySelector('input[type="text"]') : this.$el;

                  el[this.isFocused ? 'focus' : 'blur']();

                  // restore query value in filterable single selects
                  const [selectedOption] = this.values;
                  if (selectedOption && this.filterable && !this.multiple && !focused){

                      const selectedLabel = String(selectedOption.label || selectedOption.value).trim();

                      if (selectedLabel && this.query !== selectedLabel) {

                          this.preventRemoteCall = true;
                          this.query = selectedLabel;
                      }

                  }
              },
              focusIndex(index){

                  if (index < 0 || this.autoComplete) return;

                  // update scroll
                  const optionValue = this.flatOptions[index].componentOptions.propsData.value;
                  const optionInstance = findChild(this, ({$options}) => {
                      return $options.componentName === 'select-item' && $options.propsData.value === optionValue;
                  });

                  let bottomOverflowDistance = optionInstance.$el.getBoundingClientRect().bottom - this.$refs.dropdown.$el.getBoundingClientRect().bottom;
                  let topOverflowDistance = optionInstance.$el.getBoundingClientRect().top - this.$refs.dropdown.$el.getBoundingClientRect().top;
                  if (bottomOverflowDistance > 0) {
                      this.$refs.dropdown.$el.scrollTop += bottomOverflowDistance;
                  }
                  if (topOverflowDistance < 0) {
                      this.$refs.dropdown.$el.scrollTop += topOverflowDistance;

                  }

              },
              dropVisible(open){
                  this.broadcast('Drop', open ? 'on-update-popper' : 'on-destroy-popper');

              },

              selectOptions(){

                  if (this.hasExpectedValue && this.selectOptions.length > 0){
                      if (this.values.length === 0) {
                          this.values = this.getInitialValue();
                      }

                      this.values = this.values.map(this.getOptionData).filter(Boolean);

                      this.hasExpectedValue = false;
                  }

                  if (this.slotOptions && this.slotOptions.length === 0){

                      this.query = '';
                  }

                   // 当 dropdown 一开始在控件下部显示，而滚动页面后变成在上部显示，如果选项列表的长度由内部动态变更了(搜索情况)
                   // dropdown 的位置不会重新计算，需要重新计算

                  this.broadcast('Drop', 'on-update-popper');

              },
              visible(state){
                  this.$emit('on-open-change', state);

              },
              slotOptions(options, old){

                  // #4626，当 Options 的 label 更新时，v-model 的值未更新

                  // remote 下，调用 getInitialValue 有 bug
                  if (!this.remote) {
                      const values = this.getInitialValue();
                      if (this.flatOptions && this.flatOptions.length && values.length && !this.multiple) {
                          this.values = values.map(this.getOptionData).filter(Boolean);
                      }

                  }
  

                  // 当 dropdown 在控件上部显示时，如果选项列表的长度由外部动态变更了，
                  // dropdown 的位置会有点问题，需要重新计算
                  if (options && old && options.length !== old.length) {
                      this.broadcast('Drop', 'on-update-popper');
                  }
              },

          }

      };

  </script>