常用 js 代码片段

1. 根据url地址下载

export const download = (url) => {
    var isChrome = navigator.userAgent.toLowerCase().indexOf('chrome') > -1;
    var isSafari = navigator.userAgent.toLowerCase().indexOf('safari') > -1;
    if (isChrome || isSafari) {
        var link = document.createElement('a');
        link.href = url;
        if (link.download !== undefined) {
            var fileName = url.substring(url.lastIndexOf('/') + 1, url.length);
            link.download = fileName;
        }
        if (document.createEvent) {
            var e = document.createEvent('MouseEvents');
            e.initEvent('click', true, true);
            link.dispatchEvent(e);
            return true;
        }
    }
    if (url.indexOf('?') === -1) {
        url += '?download';
    }
    window.open(url, '_self');
    return true;
}

2. class操作
   • el是否包含某个class

export const hasClass = (el, className) => {
  let reg = new RegExp('(^|\\s)' + className + '(\\s|$)')
  return reg.test(el.className)
}

• el添加某个class

export const addClass = (el, className) => {
    if (hasClass(el, className)) {
        return
    }
    let newClass = el.className.split(' ')
    newClass.push(className)
    el.className = newClass.join(' ')
}

• el去除某个class

export const removeClass = (el, className) => {
    if (!hasClass(el, className)) {
        return
    }
    let reg = new RegExp('(^|\\s)' + className + '(\\s|$)', 'g')
    el.className = el.className.replace(reg, ' ')
}

3. 随机数范围

export const random = (min, max) => {
    if (arguments.length === 2) {
        return Math.floor(min + Math.random() * ((max + 1) - min))
    } else {
        return null;
    }
}

4. 将阿拉伯数字翻译成中文的大写数字

export const numberToChinese = (num) => {
    var AA = new Array("零", "一", "二", "三", "四", "五", "六", "七", "八", "九", "十");
    var BB = new Array("", "十", "百", "仟", "萬", "億", "点", "");
    var a = ("" + num).replace(/(^0*)/g, "").split("."),
        k = 0,
        re = "";
    for (var i = a[0].length - 1; i >= 0; i--) {
        switch (k) {
            case 0:
                re = BB[7] + re;
                break;
            case 4:
                if (!new RegExp("0{4}//d{" + (a[0].length - i - 1) + "}$")
                    .test(a[0]))
                    re = BB[4] + re;
                break;
            case 8:
                re = BB[5] + re;
                BB[7] = BB[5];
                k = 0;
                break;
        }
        if (k % 4 == 2 && a[0].charAt(i + 2) != 0 && a[0].charAt(i + 1) == 0)
            re = AA[0] + re;
        if (a[0].charAt(i) != 0)
            re = AA[a[0].charAt(i)] + BB[k % 4] + re;
        k++;
    }

    if (a.length > 1) // 加上小数部分(如果有小数部分)
    {
        re += BB[6];
        for (var i = 0; i < a[1].length; i++)
            re += AA[a[1].charAt(i)];
    }
    if (re == '一十')
        re = "十";
    if (re.match(/^一/) && re.length == 3)
        re = re.replace("一", "");
    return re;
}

5. 将数字转换为大写金额

export const changeToChinese = (Num) => {
    //判断如果传递进来的不是字符的话转换为字符
    if (typeof Num == "number") {
        Num = new String(Num);
    };
    Num = Num.replace(/,/g, "") //替换tomoney()中的“,”
    Num = Num.replace(/ /g, "") //替换tomoney()中的空格
    Num = Num.replace(/￥/g, "") //替换掉可能出现的￥字符
    if (isNaN(Num)) { //验证输入的字符是否为数字
        //alert("请检查小写金额是否正确");
        return "";
    };
    //字符处理完毕后开始转换，采用前后两部分分别转换
    var part = String(Num).split(".");
    var newchar = "";
    //小数点前进行转化
    for (var i = part[0].length - 1; i >= 0; i--) {
        if (part[0].length > 10) {
            return "";
            //若数量超过拾亿单位，提示
        }
        var tmpnewchar = ""
        var perchar = part[0].charAt(i);
        switch (perchar) {
            case "0":
                tmpnewchar = "零" + tmpnewchar;
                break;
            case "1":
                tmpnewchar = "壹" + tmpnewchar;
                break;
            case "2":
                tmpnewchar = "贰" + tmpnewchar;
                break;
            case "3":
                tmpnewchar = "叁" + tmpnewchar;
                break;
            case "4":
                tmpnewchar = "肆" + tmpnewchar;
                break;
            case "5":
                tmpnewchar = "伍" + tmpnewchar;
                break;
            case "6":
                tmpnewchar = "陆" + tmpnewchar;
                break;
            case "7":
                tmpnewchar = "柒" + tmpnewchar;
                break;
            case "8":
                tmpnewchar = "捌" + tmpnewchar;
                break;
            case "9":
                tmpnewchar = "玖" + tmpnewchar;
                break;
        }
        switch (part[0].length - i - 1) {
            case 0:
                tmpnewchar = tmpnewchar + "元";
                break;
            case 1:
                if (perchar != 0) tmpnewchar = tmpnewchar + "拾";
                break;
            case 2:
                if (perchar != 0) tmpnewchar = tmpnewchar + "佰";
                break;
            case 3:
                if (perchar != 0) tmpnewchar = tmpnewchar + "仟";
                break;
            case 4:
                tmpnewchar = tmpnewchar + "万";
                break;
            case 5:
                if (perchar != 0) tmpnewchar = tmpnewchar + "拾";
                break;
            case 6:
                if (perchar != 0) tmpnewchar = tmpnewchar + "佰";
                break;
            case 7:
                if (perchar != 0) tmpnewchar = tmpnewchar + "仟";
                break;
            case 8:
                tmpnewchar = tmpnewchar + "亿";
                break;
            case 9:
                tmpnewchar = tmpnewchar + "拾";
                break;
        }
        var newchar = tmpnewchar + newchar;
    }
    //小数点之后进行转化
    if (Num.indexOf(".") != -1) {
        if (part[1].length > 2) {
            // alert("小数点之后只能保留两位,系统将自动截断");
            part[1] = part[1].substr(0, 2)
        }
        for (i = 0; i < part[1].length; i++) {
            tmpnewchar = ""
            perchar = part[1].charAt(i)
            switch (perchar) {
                case "0":
                    tmpnewchar = "零" + tmpnewchar;
                    break;
                case "1":
                    tmpnewchar = "壹" + tmpnewchar;
                    break;
                case "2":
                    tmpnewchar = "贰" + tmpnewchar;
                    break;
                case "3":
                    tmpnewchar = "叁" + tmpnewchar;
                    break;
                case "4":
                    tmpnewchar = "肆" + tmpnewchar;
                    break;
                case "5":
                    tmpnewchar = "伍" + tmpnewchar;
                    break;
                case "6":
                    tmpnewchar = "陆" + tmpnewchar;
                    break;
                case "7":
                    tmpnewchar = "柒" + tmpnewchar;
                    break;
                case "8":
                    tmpnewchar = "捌" + tmpnewchar;
                    break;
                case "9":
                    tmpnewchar = "玖" + tmpnewchar;
                    break;
            }
            if (i == 0) tmpnewchar = tmpnewchar + "角";
            if (i == 1) tmpnewchar = tmpnewchar + "分";
            newchar = newchar + tmpnewchar;
        }
    }
    //替换所有无用汉字
    while (newchar.search("零零") != -1)
        newchar = newchar.replace("零零", "零");
    newchar = newchar.replace("零亿", "亿");
    newchar = newchar.replace("亿万", "亿");
    newchar = newchar.replace("零万", "万");
    newchar = newchar.replace("零元", "元");
    newchar = newchar.replace("零角", "");
    newchar = newchar.replace("零分", "");
    if (newchar.charAt(newchar.length - 1) == "元") {
        newchar = newchar + "整"
    }
    return newchar;
}

6. 数组

• 判断一个元素是否在数组中

export const contains = (arr, val) => {
    return arr.indexOf(val) != -1 ? true : false;
}

• 最大值

export const max = (arr) => {
    return Math.max.apply(null, arr);
}

• 最小值

export const min = (arr) => {
    return Math.min.apply(null, arr);
}

• 数组排序，{type} 1：从小到大 2：从大到小 3：随机

export const sort = (arr, type = 1) => {
    return arr.sort((a, b) => {
        switch (type) {
            case 1:
                return a - b;
            case 2:
                return b - a;
            case 3:
                return Math.random() - 0.5;
            default:
                return arr;
        }
    })
}

• 去重

export const unique = (arr) => {
    if (Array.hasOwnProperty('from')) {
        return Array.from(new Set(arr));
    } else {
        var n = {}, r = [];
        for (var i = 0; i < arr.length; i++) {
            if (!n[arr[i]]) {
                n[arr[i]] = true;
                r.push(arr[i]);
            }
        }
        return r;
    }
}

• 求两个集合的并集

export const union = (a, b) => {
    var newArr = a.concat(b);
    return this.unique(newArr);
}

• 求两个集合的交集

export const intersect = (a, b) => {
    var _this = this;
    a = this.unique(a);
    return this.map(a, function (o) {
        return _this.contains(b, o) ? o : null;
    });
}

7. 字符串

• 去除空格,type: 1-所有空格 2-前后空格 3-前空格 4-后空格

export const trim = (str, type) => {
    type = type || 1
    switch (type) {
        case 1:
            return str.replace(/\s+/g, "");
        case 2:
            return str.replace(/(^\s*)|(\s*$)/g, "");
        case 3:
            return str.replace(/(^\s*)/g, "");
        case 4:
            return str.replace(/(\s*$)/g, "");
        default:
            return str;
    }
}

• 字符转换，type: 1:首字母大写 2：首字母小写 3：大小写转换 4：全部大写 5：全部小写

export const changeCase = (str, type) => {
    type = type || 4
    switch (type) {
        case 1:
            return str.replace(/\b\w+\b/g, function (word) {
                return word.substring(0, 1).toUpperCase() + word.substring(1).toLowerCase();

            });
        case 2:
            return str.replace(/\b\w+\b/g, function (word) {
                return word.substring(0, 1).toLowerCase() + word.substring(1).toUpperCase();
            });
        case 3:
            return str.split('').map(function (word) {
                if (/[a-z]/.test(word)) {
                    return word.toUpperCase();
                } else {
                    return word.toLowerCase()
                }
            }).join('')
        case 4:
            return str.toUpperCase();
        case 5:
            return str.toLowerCase();
        default:
            return str;
    }
}