src/utils/assist.js

// 判断参数是否是其中之一
export function oneOf (value, validList) {
    for (let i = 0; i < validList.length; i++) {
        if (value === validList[i]) {
            return true;
        }
    }
    return false;
}
export function camelcaseToHyphen (str) {
    return str.replace(/([a-z])([A-Z])/g, '$1-$2').toLowerCase();
}
// For Modal scrollBar hidden
let cached;
export function getScrollBarSize (fresh) {
    if (fresh || cached === undefined) {
        const inner = document.createElement('div');
        inner.style.width = '100%';
        inner.style.height = '200px';
        const outer = document.createElement('div');
        const outerStyle = outer.style;
        outerStyle.position = 'absolute';
        outerStyle.top = 0;
        outerStyle.left = 0;
        outerStyle.pointerEvents = 'none';
        outerStyle.visibility = 'hidden';
        outerStyle.width = '200px';
        outerStyle.height = '150px';
        outerStyle.overflow = 'hidden';
        outer.appendChild(inner);
        document.body.appendChild(outer);
        const widthContained = inner.offsetWidth;
        outer.style.overflow = 'scroll';
        let widthScroll = inner.offsetWidth;
        if (widthContained === widthScroll) {
            widthScroll = outer.clientWidth;
        }
        document.body.removeChild(outer);
        cached = widthContained - widthScroll;
    }
    return cached;
}
// watch DOM change
export const MutationObserver = window.MutationObserver || window.WebKitMutationObserver || window.MozMutationObserver || false;
const SPECIAL_CHARS_REGEXP = /([\:\-\_]+(.))/g;
const MOZ_HACK_REGEXP = /^moz([A-Z])/;
function camelCase(name) {
    return name.replace(SPECIAL_CHARS_REGEXP, function(_, separator, letter, offset) {
        return offset ? letter.toUpperCase() : letter;
    }).replace(MOZ_HACK_REGEXP, 'Moz$1');
}
// getStyle
export function getStyle (element, styleName) {
    if (!element || !styleName) return null;
    styleName = camelCase(styleName);
    if (styleName === 'float') {
        styleName = 'cssFloat';
    }
    try {
        const computed = document.defaultView.getComputedStyle(element, '');
        return element.style[styleName] || computed ? computed[styleName] : null;
    } catch(e) {
        return element.style[styleName];
    }
}
// firstUpperCase
function firstUpperCase(str) {
    return str.toString()[0].toUpperCase() + str.toString().slice(1);
}
export {firstUpperCase};
// Warn
export function warnProp(component, prop, correctType, wrongType) {
    correctType = firstUpperCase(correctType);
    wrongType = firstUpperCase(wrongType);
    console.error(`[iView warn]: Invalid prop: type check failed for prop ${prop}. Expected ${correctType}, got ${wrongType}. (found in component: ${component})`);    // eslint-disable-line
}
function typeOf(obj) {
    const toString = Object.prototype.toString;
    const map = {
        '[object Boolean]'  : 'boolean',
        '[object Number]'   : 'number',
        '[object String]'   : 'string',
        '[object Function]' : 'function',
        '[object Array]'    : 'array',
        '[object Date]'     : 'date',
        '[object RegExp]'   : 'regExp',
        '[object Undefined]': 'undefined',
        '[object Null]'     : 'null',
        '[object Object]'   : 'object'
    };
    return map[toString.call(obj)];
}
// deepCopy
function deepCopy(data) {
    const t = typeOf(data);
    let o;
    if (t === 'array') {
        o = [];
    } else if ( t === 'object') {
        o = {};
    } else {
        return data;
    }
    if (t === 'array') {
        for (let i = 0; i < data.length; i++) {
            o.push(deepCopy(data[i]));
        }
    } else if ( t === 'object') {
        for (let i in data) {
            o[i] = deepCopy(data[i]);
        }
    }
    return o;
}
export {deepCopy};
// scrollTop animation
export function scrollTop(el, from = 0, to, duration = 500) {
    if (!window.requestAnimationFrame) {
        window.requestAnimationFrame = (
            window.webkitRequestAnimationFrame ||
            window.mozRequestAnimationFrame ||
            window.msRequestAnimationFrame ||
            function (callback) {
                return window.setTimeout(callback, 1000/60);
            }
        );
    }
    const difference = Math.abs(from - to);
    const step = Math.ceil(difference / duration * 50);
    function scroll(start, end, step) {
        if (start === end) return;
        let d = (start + step > end) ? end : start + step;
        if (start > end) {
            d = (start - step < end) ? end : start - step;
        }
        if (el === window) {
            window.scrollTo(d, d);
        } else {
            el.scrollTop = d;
        }
        window.requestAnimationFrame(() => scroll(d, end, step));
    }
    scroll(from, to, step);
}