和业务相关的工具函数

// 获取字符长度
export function getStringLen (str) {
    let len = 0;
    for (let i = 0; i < str.length; i++) {
        if (str.charCodeAt(i) > 127 || str.charCodeAt(i) == 94) {
            len += 2;
        } else {
            len ++;
        }
    }
    return len;
}

【距离今天多久之前的时间段，关键点是把时间都以毫秒换算】

/**
 * @description 获取距离今天多久之前的时间段
 * @param {Number} unit  单位    0: 天   1: 周   2: 月
 * @param {Number} count 数值
 * @returns {Array} [yyyy-MM-dd, yyyy-MM-dd]
 */
export function sinceToday(unit, count) {
    const DAY = 60 * 60 * 24 * 1000;
    const endTime = new Date();
    let startTime = null;

    endTime.setDate(endTime.getDate() + 1);
    endTime.setHours(0);
    endTime.setMinutes(0);
    endTime.setSeconds(0);
    endTime.setMilliseconds(0);

    switch (unit) {
        case 0:     // 天
            startTime = endTime.getTime() - count * DAY;

            break;
        case 1:     // 周
            startTime = endTime.getTime() - count * DAY * 7;

            break;

        case 2:     // 月
            const currentMonth = endTime.getMonth();
            startTime = new Date().setMonth(currentMonth - count);

            break;

        default:
            startTime = endTime.getTime();

            break;
    }

    if (unit === 0) {
        // 今天
        if (count === 0) {
            return [number2DateTime( new Date().getTime(), 'yyyy-MM-dd'), number2DateTime( new Date().getTime(), 'yyyy-MM-dd')];
        }

        // 昨天
        if (count === 1) {
            return [number2DateTime(startTime - 1, 'yyyy-MM-dd'), number2DateTime(startTime - 1, 'yyyy-MM-dd')];
        }
    }

    return [number2DateTime(startTime + DAY - 1, 'yyyy-MM-dd'), number2DateTime(endTime.getTime() - 1, 'yyyy-MM-dd')];
}

【深层遍历数据，将深层结构拆成扁平结构，并利用了数据引用类型的特点】

/**
 * 
 * @param {Array} data              被遍历的数据
 * @param {Function} callback       遍历到某个结点时要执行的回调，三个回调参数为 当前结点、当前结点在父元素中的下标、父元素
 * @param {String} childkey         存储子结点的属性值
 */
export function traversalTree(data, callback, childkey = 'ChildrenList') {
    const queue = [data];

    while (queue.length) {
        const nodes = queue.shift();

        for (let i = nodes.length - 1; i >= 0; i--) {
            nodes[i][childkey] && queue.push(nodes[i][childkey]);
            callback(nodes[i], i, nodes);
        }
    }
}

【深度复制】

// 深复制

export function clone(obj) {

    var copy;
    // Handle the 3 simple types, and null or undefined
    if (null == obj || "object" != typeof obj) return obj;

    // Handle Date
    if (obj instanceof Date) {
        copy = new Date();
        copy.setTime(obj.getTime());
        return copy;
    }

    // Handle Array
    if (obj instanceof Array) {
        copy = [];
        for (var i = 0, len = obj.length; i < len; i++) {
            copy[i] = clone(obj[i]);
        }
        return copy;
    }

    // Handle Object
    if (obj instanceof Object) {
        copy = {};
        for (var attr in obj) {
            if (obj.hasOwnProperty(attr)) copy[attr] = clone(obj[attr]);
        }
        return copy;
    }

    throw new Error("Unable to copy obj! Its type isn't supported.");
}

【对象比较】

export function diff(obj1, obj2) { // 对象比较
    var o1 = obj1 instanceof Object;
    var o2 = obj2 instanceof Object;
    if (!o1 || !o2) { /*  判断不是对象  */
        return obj1 === obj2;
    }

    if (Object.keys(obj1).length !== Object.keys(obj2).length) {
        return false;
        //Object.keys() 返回一个由对象的自身可枚举属性(key值)组成的数组,例如：数组返回下表：let arr = ["a", "b", "c"];console.log(Object.keys(arr))->0,1,2;
    }

    for (var attr in obj1) {
        var t1 = obj1[attr] instanceof Object;
        var t2 = obj2[attr] instanceof Object;
        if (t1 && t2) {
            return diff(obj1[attr], obj2[attr]);
        } else if (!obj1[attr] && !obj2[attr]) {
            continue;
        } else if (obj1[attr] !== obj2[attr]) {
            return false;
        }
    }
    return true;
}

【判断对象类型】

// 对象类型
function is(type, obj) {
    var clas = Object.prototype.toString.call(obj).slice(8, -1);
    return obj !== undefined && obj !== null && clas === type;
}

【防抖】

export function debounce(func, wait, immediate) {
    let timeout, args, context, timestamp, result

    const later = function() {
        // 据上一次触发时间间隔
        const last = +new Date() - timestamp

        // 上次被包装函数被调用时间间隔last小于设定时间间隔wait
        if (last < wait && last > 0) {
            timeout = setTimeout(later, wait - last)
        } else {
            timeout = null
            // 如果设定为immediate===true，因为开始边界已经调用过了此处无需调用
            if (!immediate) {
                result = func.apply(context, args)
                if (!timeout) context = args = null
            }
        }
    }

    return function(...args) {
        context = this
        timestamp = +new Date()
        const callNow = immediate && !timeout
            // 如果延时不存在，重新设定延时
        if (!timeout) timeout = setTimeout(later, wait)
        if (callNow) {
            result = func.apply(context, args)
            context = args = null
        }

        return result
    }
}

【时间格式化】

export function number2DateTime(value, fmt = 'yyyy-MM-dd HH:mm:ss') { // yyyy-MM-dd HH:mm:ss
    if (isNaN(value) || value == null) return '';
    const date = new Date(Number(value));
    const year = date.getFullYear();
    const month = date.getMonth() + 1;
    const day = date.getDate();
    const hour = date.getHours();
    const minute = date.getMinutes();
    const second = date.getSeconds();
    return fmt.replace('yyyy', year.toString())
        .replace('yy', (year % 100).toString())
        .replace('MM', month > 9 ? month.toString() : ("0" + month))
        .replace('dd', day > 9 ? day.toString() : ("0" + day))
        .replace('HH', hour > 9 ? (hour).toString() : ("0" + hour))
        .replace('mm', minute > 9 ? (minute).toString() : ("0" + minute))
        .replace('ss', second > 9 ? (second).toString() : ("0" + second));
}

【去掉空格】

export function trim(str) { // 去空格
    if(str == null) return
    return str.replace(/s/g, '');
}

【距离当前多少天】

/**
 * @description 距离现在多少天
 * @params { String } dateStr 比如 2010-12-12 12:34:21
*/
export function getDaysFromNow(dateStr) {
    let d = new Date();
    let dEnd = new Date(`${d.getFullYear()}-${(d.getMonth() + 1)}-${d.getDate()} 00:00:00`).getTime();

    let ds = new Date(dateStr);
    let dStart = new Date(`${ds.getFullYear()}-${(ds.getMonth() + 1)}-${ds.getDate()} 00:00:00`).getTime();

    let dSpan = Math.abs(dEnd - dStart);

    return Math.floor(dSpan / (24 * 3600 * 1000));
}