back-top.vue
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<template>
<div :class="classes" :style="styles" @click="back">
<slot>
<div :class="innerClasses">
<i class="ivu-icon ivu-icon-chevron-up"></i>
</div>
</slot>
</div>
</template>
<script>
const prefixCls = 'ivu-back-top';
function getScroll(target, top) {
const prop = top ? 'pageYOffset' : 'pageXOffset';
const method = top ? 'scrollTop' : 'scrollLeft';
let ret = target[prop];
if (typeof ret !== 'number') {
ret = window.document.documentElement[method];
}
return ret;
}
export default {
props: {
height: {
type: Number,
default: 400
},
bottom: {
type: Number,
default: 30
},
right: {
type: Number,
default: 30
}
},
data () {
return {
backTop: false
}
},
ready () {
window.addEventListener('scroll', this.handleScroll, false);
window.addEventListener('resize', this.handleScroll, false);
},
beforeDestroy () {
window.removeEventListener('scroll', this.handleScroll, false);
window.removeEventListener('resize', this.handleScroll, false);
},
computed: {
classes () {
return [
`${prefixCls}`,
{
[`${prefixCls}-show`]: this.backTop
}
]
},
styles () {
return {
bottom: `${this.bottom}px`,
right: `${this.right}px`
}
},
innerClasses () {
return `${prefixCls}-inner`;
}
},
methods: {
handleScroll () {
const backTop = this.backTop;
const scrollTop = getScroll(window, true);
if (this.height <= scrollTop && !backTop) {
this.backTop = true;
} else if (this.height > scrollTop && backTop) {
this.backTop = false;
}
},
back () {
window.scrollTo(0, 0);
this.$emit('on-click');
}
}
}
</script>