JS開(kāi)發(fā)常用工具函數(shù)

whlong 發(fā)布于2019-08-23 18:20 / 453人閱讀

摘要：檢測(cè)數(shù)據(jù)是不是除了外的原始數(shù)據(jù)檢測(cè)數(shù)據(jù)是不是原始數(shù)據(jù)判斷數(shù)據(jù)是不是引用類型的數(shù)據(jù)例如以及檢查是否是類對(duì)象。返回一個(gè)布爾值，表示該值是否為的成員。

1、isStatic：檢測(cè)數(shù)據(jù)是不是除了symbol外的原始數(shù)據(jù)

function isStatic(value) {
    return(
        typeof value === "string" ||
        typeof value === "number" ||
        typeof value === "boolean" ||
        typeof value === "undefined" ||
        value === null
    )
}

2、isPrimitive：檢測(cè)數(shù)據(jù)是不是原始數(shù)據(jù)

function isPrimitive(value) {
    return isStatic(value) || typeof value === "symbol"
}

3、isObject：判斷數(shù)據(jù)是不是引用類型的數(shù)據(jù) (例如： arrays, functions, objects, regexes, new Number(0),以及 new String(""))

function isObject(value) {
      let type = typeof value;
      return value != null && (type == "object" || type == "function");
}

4、isObjectLike：檢查 value 是否是類對(duì)象。如果一個(gè)值是類對(duì)象，那么它不應(yīng)該是 null，而且 typeof 后的結(jié)果是 "object"

function isObjectLike(value) {
      return value != null && typeof value == "object";
}

5、getRawType：獲取數(shù)據(jù)類型，返回結(jié)果為 Number、String、Object、Array等

function getRawType(value) {
    return Object.prototype.toString.call(value).slice(8, -1)
}
//getoRawType([]) ==> Array

6、isPlainObject：判斷數(shù)據(jù)是不是Object類型的數(shù)據(jù)

function isPlainObject(obj) {
    return Object.prototype.toString.call(obj) === "[object Object]"
}

7、isArray：判斷數(shù)據(jù)是不是數(shù)組類型的數(shù)據(jù)

function isArray(arr) {
    return Object.prototype.toString.call(arr) === "[object Array]"
}

將isArray掛載到Array上

Array.isArray = Array.isArray || isArray;

8、isRegExp：判斷數(shù)據(jù)是不是正則對(duì)象

function isRegExp(value) {
    return Object.prototype.toString.call(value) === "[object RegExp]"
}

9、isDate：判斷數(shù)據(jù)是不是時(shí)間對(duì)象

function isDate(value) {
    return Object.prototype.toString.call(value) === "[object Date]"
}

10、isNative：判斷 value 是不是瀏覽器內(nèi)置函數(shù)

內(nèi)置函數(shù)toString后的主體代碼塊為 [native code] ，而非內(nèi)置函數(shù)則為相關(guān)代碼，所以非內(nèi)置函數(shù)可以進(jìn)行拷貝(toString后掐頭去尾再由Function轉(zhuǎn))

function isNative(value) {
    return typeof value === "function" && /native code/.test(value.toString())
}

11、isFunction：檢查 value 是不是函數(shù)

function isFunction(value) {
    return Object.prototype.toString.call(value) === "[object Function]"
}

12、isLength：檢查 value 是否為有效的類數(shù)組長(zhǎng)度

function isLength(value) {
      return typeof value == "number" && value > -1 && value % 1 == 0 && value <= Number.MAX_SAFE_INTEGER;
}

13、isArrayLike：檢查 value 是否是類數(shù)組

如果一個(gè)值被認(rèn)為是類數(shù)組，那么它不是一個(gè)函數(shù)，并且value.length是個(gè)整數(shù)，大于等于 0，小于或等于 Number.MAX_SAFE_INTEGER。這里字符串也將被當(dāng)作類數(shù)組

function isArrayLike(value) {
      return value != null && isLength(value.length) && !isFunction(value);
}

14、isEmpty：檢查 value 是否為空

如果是null，直接返回true；如果是類數(shù)組，判斷數(shù)據(jù)長(zhǎng)度；如果是Object對(duì)象，判斷是否具有屬性；如果是其他數(shù)據(jù)，直接返回false(也可改為返回true)

function isEmpty(value) {
    if (value == null) {
        return true;
    }
    if (isArrayLike(value)) {
        return !value.length;
    }else if(isPlainObject(value)){
          for (let key in value) {
            if (hasOwnProperty.call(value, key)) {
              return false;
            }
        }
        return true;
    }
    return false;
}

15、cached：記憶函數(shù)：緩存函數(shù)的運(yùn)算結(jié)果

function cached(fn) {
    let cache = Object.create(null);
    return function cachedFn(str) {
        let hit = cache[str];
        return hit || (cache[str] = fn(str))
    }
}

16、camelize：橫線轉(zhuǎn)駝峰命名

let camelizeRE = /-(w)/g;
function camelize(str) {
    return str.replace(camelizeRE, function(_, c) {
        return c ? c.toUpperCase() : "";
    })
}
//ab-cd-ef ==> abCdEf
//使用記憶函數(shù)
let _camelize = cached(camelize)

17、hyphenate：駝峰命名轉(zhuǎn)橫線命名：拆分字符串，使用 - 相連，并且轉(zhuǎn)換為小寫(xiě)

let hyphenateRE = /B([A-Z])/g;
function hyphenate(str){
    return str.replace(hyphenateRE, "-$1").toLowerCase()
}
//abCd ==> ab-cd
//使用記憶函數(shù)
let _hyphenate = cached(hyphenate);

18、capitalize：字符串首位大寫(xiě)

function capitalize(str){
    return str.charAt(0).toUpperCase() + str.slice(1)
}
// abc ==> Abc
//使用記憶函數(shù)
let _capitalize = cached(capitalize)

19、extend：將屬性混合到目標(biāo)對(duì)象中

function extend(to, _from) {
    for(let key in _from) {
        to[key] = _from[key];
    }
    return to
}

20、Object.assign：對(duì)象屬性復(fù)制，淺拷貝

Object.assign = Object.assign || function(){
    if(arguments.length == 0) throw new TypeError("Cannot convert undefined or null to object");
    
    let target = arguments[0],
        args = Array.prototype.slice.call(arguments, 1),
        key
    args.forEach(function(item){
        for(key in item){
            item.hasOwnProperty(key) && ( target[key] = item[key] )
        }
    })
    return target
}

使用Object.assign可以淺克隆一個(gè)對(duì)象：

let clone = Object.assign({}, target)

簡(jiǎn)單的深克隆可以使用JSON.parse()和JSON.stringify()，這兩個(gè)api是解析json數(shù)據(jù)的，所以只能解析除symbol外的原始類型及數(shù)組和對(duì)象

let clone = JSON.parse( JSON.stringify(target) )

21、clone：克隆數(shù)據(jù)，可深度克隆

這里列出了原始類型，時(shí)間、正則、錯(cuò)誤、數(shù)組、對(duì)象的克隆規(guī)則，其他的可自行補(bǔ)充

function clone(value, deep){
    if(isPrimitive(value)){
        return value
    }
    
    if (isArrayLike(value)) { //是類數(shù)組
        value = Array.prototype.slice.call(value)
        return value.map(item => deep ? clone(item, deep) : item)
       }else if(isPlainObject(value)){ //是對(duì)象
           let target = {}, key;
          for (key in value) {
            value.hasOwnProperty(key) && ( target[key] = deep ? clone(value[key], deep) : value[key] )
        }
    }
    
    let type = getRawType(value)
    
    switch(type){
        case "Date":
        case "RegExp": 
        case "Error": value = new window[type](value); break;
    }
    return value
}

22、識(shí)別各種瀏覽器及平臺(tái)

//運(yùn)行環(huán)境是瀏覽器
let inBrowser = typeof window !== "undefined";
//運(yùn)行環(huán)境是微信
let inWeex = typeof WXEnvironment !== "undefined" && !!WXEnvironment.platform;
let weexPlatform = inWeex && WXEnvironment.platform.toLowerCase();
//瀏覽器 UA 判斷
let UA = inBrowser && window.navigator.userAgent.toLowerCase();
let isIE = UA && /msie|trident/.test(UA);
let isIE9 = UA && UA.indexOf("msie 9.0") > 0;
let isEdge = UA && UA.indexOf("edge/") > 0;
let isAndroid = (UA && UA.indexOf("android") > 0) || (weexPlatform === "android");
let isIOS = (UA && /iphone|ipad|ipod|ios/.test(UA)) || (weexPlatform === "ios");
let isChrome = UA && /chrome/d+/.test(UA) && !isEdge;

23、getExplorerInfo：獲取瀏覽器信息

function getExplorerInfo() {
    let t = navigator.userAgent.toLowerCase();
    return 0 <= t.indexOf("msie") ? { //ie < 11
        type: "IE",
        version: Number(t.match(/msie ([d]+)/)[1])
    } : !!t.match(/trident/.+?rv:(([d.]+))/) ? { // ie 11
        type: "IE",
        version: 11
    } : 0 <= t.indexOf("edge") ? {
        type: "Edge",
        version: Number(t.match(/edge/([d]+)/)[1])
    } : 0 <= t.indexOf("firefox") ? {
        type: "Firefox",
        version: Number(t.match(/firefox/([d]+)/)[1])
    } : 0 <= t.indexOf("chrome") ? {
        type: "Chrome",
        version: Number(t.match(/chrome/([d]+)/)[1])
    } : 0 <= t.indexOf("opera") ? {
        type: "Opera",
        version: Number(t.match(/opera.([d]+)/)[1])
    } : 0 <= t.indexOf("Safari") ? {
        type: "Safari",
        version: Number(t.match(/version/([d]+)/)[1])
    } : {
        type: t,
        version: -1
    }
}

24、isPCBroswer：檢測(cè)是否為PC端瀏覽器模式

function isPCBroswer() {
    let e = navigator.userAgent.toLowerCase()
        , t = "ipad" == e.match(/ipad/i)
        , i = "iphone" == e.match(/iphone/i)
        , r = "midp" == e.match(/midp/i)
        , n = "rv:1.2.3.4" == e.match(/rv:1.2.3.4/i)
        , a = "ucweb" == e.match(/ucweb/i)
        , o = "android" == e.match(/android/i)
        , s = "windows ce" == e.match(/windows ce/i)
        , l = "windows mobile" == e.match(/windows mobile/i);
    return !(t || i || r || n || a || o || s || l)
}

25、unique：數(shù)組去重，返回一個(gè)新數(shù)組

function unique(arr){
    if(!isArrayLink(arr)){ //不是類數(shù)組對(duì)象
        return arr
    }
    let result = []
    let objarr = []
    let obj = Object.create(null)
    
    arr.forEach(item => {
        if(isStatic(item)){//是除了symbol外的原始數(shù)據(jù)
            let key = item + "_" + getRawType(item);
            if(!obj[key]){
                obj[key] = true
                result.push(item)
            }
        }else{//引用類型及symbol
            if(!objarr.includes(item)){
                objarr.push(item)
                result.push(item)
            }
        }
    })
    
    return resulte
}

26、Set簡(jiǎn)單實(shí)現(xiàn)

window.Set = window.Set || (function () {
    function Set(arr) {
        this.items = arr ? unique(arr) : [];
        this.size = this.items.length; // Array的大小
    }
    Set.prototype = {
        add: function (value) {
            // 添加元素,若元素已存在,則跳過(guò)，返回 Set 結(jié)構(gòu)本身。
            if (!this.has(value)) {
                this.items.push(value);
                this.size++;
            }
            return this;
        },
        clear: function () {
            //清除所有成員，沒(méi)有返回值。
            this.items = []
            this.size = 0
        },
        delete: function (value) {
            //刪除某個(gè)值，返回一個(gè)布爾值，表示刪除是否成功。
            return this.items.some((v, i) => {
                if(v === value){
                    this.items.splice(i,1)
                    return true
                }
                return false
            })
        },
        has: function (value) {
            //返回一個(gè)布爾值，表示該值是否為Set的成員。
            return this.items.some(v => v === value)
        },
        values: function () {
            return this.items
        },
    }

    return Set;
}());

27、repeat：生成一個(gè)重復(fù)的字符串，有n個(gè)str組成，可修改為填充為數(shù)組等

function repeat(str, n) {
    let res = "";
    while(n) {
        if(n % 2 === 1) {
            res += str;
        }
        if(n > 1) {
            str += str;
        }
        n >>= 1;
    }
    return res
};
//repeat("123",3) ==> 123123123

28、dateFormater：格式化時(shí)間

function dateFormater(formater, t){
    let date = t ? new Date(t) : new Date(),
        Y = date.getFullYear() + "",
        M = date.getMonth() + 1,
        D = date.getDate(),
        H = date.getHours(),
        m = date.getMinutes(),
        s = date.getSeconds();
    return formater.replace(/YYYY|yyyy/g,Y)
        .replace(/YY|yy/g,Y.substr(2,2))
        .replace(/MM/g,(M<10?"0":"") + M)
        .replace(/DD/g,(D<10?"0":"") + D)
        .replace(/HH|hh/g,(H<10?"0":"") + H)
        .replace(/mm/g,(m<10?"0":"") + m)
        .replace(/ss/g,(s<10?"0":"") + s)
}
// dateFormater("YYYY-MM-DD HH:mm", t) ==> 2019-06-26 18:30
// dateFormater("YYYYMMDDHHmm", t) ==> 201906261830

29、dateStrForma：將指定字符串由一種時(shí)間格式轉(zhuǎn)化為另一種

from的格式應(yīng)對(duì)應(yīng)str的位置

function dateStrForma(str, from, to){
    //"20190626" "YYYYMMDD" "YYYY年MM月DD日"
    str += ""
    let Y = ""
    if(~(Y = from.indexOf("YYYY"))){
        Y = str.substr(Y, 4)
        to = to.replace(/YYYY|yyyy/g,Y)
    }else if(~(Y = from.indexOf("YY"))){
        Y = str.substr(Y, 2)
        to = to.replace(/YY|yy/g,Y)
    }

    let k,i
    ["M","D","H","h","m","s"].forEach(s =>{
        i = from.indexOf(s+s)
        k = ~i ? str.substr(i, 2) : ""
        to = to.replace(s+s, k)
    })
    return to
}
// dateStrForma("20190626", "YYYYMMDD", "YYYY年MM月DD日") ==> 2019年06月26日
// dateStrForma("121220190626", "----YYYYMMDD", "YYYY年MM月DD日") ==> 2019年06月26日
// dateStrForma("2019年06月26日", "YYYY年MM月DD日", "YYYYMMDD") ==> 20190626

// 一般的也可以使用正則來(lái)實(shí)現(xiàn)
//"2019年06月26日".replace(/(d{4})年(d{2})月(d{2})日/, "$1-$2-$3") ==> 2019-06-26

30、getPropByPath：根據(jù)字符串路徑獲取對(duì)象屬性 : "obj[0].count"

function getPropByPath(obj, path, strict) {
      let tempObj = obj;
      path = path.replace(/[(w+)]/g, ".$1"); //將[0]轉(zhuǎn)化為.0
      path = path.replace(/^./, ""); //去除開(kāi)頭的.

      let keyArr = path.split("."); //根據(jù).切割
      let i = 0;
      for (let len = keyArr.length; i < len - 1; ++i) {
        if (!tempObj && !strict) break;
        let key = keyArr[i];
        if (key in tempObj) {
            tempObj = tempObj[key];
        } else {
            if (strict) {//開(kāi)啟嚴(yán)格模式，沒(méi)找到對(duì)應(yīng)key值，拋出錯(cuò)誤
                throw new Error("please transfer a valid prop path to form item!");
            }
            break;
        }
      }
      return {
        o: tempObj, //原始數(shù)據(jù)
        k: keyArr[i], //key值
        v: tempObj ? tempObj[keyArr[i]] : null // key值對(duì)應(yīng)的值
      };
};

31、GetUrlParam：獲取Url參數(shù)，返回一個(gè)對(duì)象

function GetUrlParam(){
    let url = document.location.toString();
    let arrObj = url.split("?");
    let params = Object.create(null)
    if (arrObj.length > 1){
        arrObj = arrObj[1].split("&");
        arrObj.forEach(item=>{
            item = item.split("=");
            params[item[0]] = item[1]
        })
    }
    return params;
}
// ?a=1&b=2&c=3 ==> {a: "1", b: "2", c: "3"}

32、downloadFile：base64數(shù)據(jù)導(dǎo)出文件，文件下載

function downloadFile(filename, data){
    let DownloadLink = document.createElement("a");

    if ( DownloadLink ){
        document.body.appendChild(DownloadLink);
        DownloadLink.style = "display: none";
        DownloadLink.download = filename;
        DownloadLink.href = data;

        if ( document.createEvent ){
            let DownloadEvt = document.createEvent("MouseEvents");

            DownloadEvt.initEvent("click", true, false);
            DownloadLink.dispatchEvent(DownloadEvt);
        }
        else if ( document.createEventObject )
            DownloadLink.fireEvent("onclick");
        else if (typeof DownloadLink.onclick == "function" )
            DownloadLink.onclick();

        document.body.removeChild(DownloadLink);
    }
}

33、toFullScreen：全屏

function toFullScreen(){
    let el = document.documentElement;
    let rfs = el.requestFullScreen || el.webkitRequestFullScreen || el.mozRequestFullScreen || el.msRequestFullScreen;

    //typeof rfs != "undefined" && rfs
    if (rfs) {
        rfs.call(el);
    }else if (typeof window.ActiveXObject !== "undefined") {
        //for IE，這里其實(shí)就是模擬了按下鍵盤(pán)的F11，使瀏覽器全屏
        let wscript = new ActiveXObject("WScript.Shell");
        if (wscript != null) {
            wscript.SendKeys("{F11}");
        }
    }else{
        alert("瀏覽器不支持全屏");
    }
}

34、exitFullscreen：退出全屏

function exitFullscreen(){
    let el = parent.document;
    let cfs = el.cancelFullScreen || el.webkitCancelFullScreen || el.mozCancelFullScreen || el.exitFullScreen;

    //typeof cfs != "undefined" && cfs
    if (cfs) {
        cfs.call(el);
    }else if (typeof window.ActiveXObject !== "undefined") {
        //for IE，這里和fullScreen相同，模擬按下F11鍵退出全屏
        let wscript = new ActiveXObject("WScript.Shell");
        if (wscript != null) {
            wscript.SendKeys("{F11}");
        }
    }else{
        alert("切換失敗,可嘗試Esc退出")
    }
}

35、requestAnimationFrame：window動(dòng)畫(huà)

window.requestAnimationFrame = window.requestAnimationFrame ||
    window.webkitRequestAnimationFrame ||
    window.mozRequestAnimationFrame ||
    window.msRequestAnimationFrame ||
    window.oRequestAnimationFrame ||
    function (callback) {
        //為了使setTimteout的盡可能的接近每秒60幀的效果
        window.setTimeout(callback, 1000 / 60);
    };
    
window.cancelAnimationFrame = window.cancelAnimationFrame ||
    Window.webkitCancelAnimationFrame ||
    window.mozCancelAnimationFrame ||
    window.msCancelAnimationFrame ||
    window.oCancelAnimationFrame ||
    function (id) {
        //為了使setTimteout的盡可能的接近每秒60幀的效果
        window.clearTimeout(id);
    }

36、_isNaN：檢查數(shù)據(jù)是否是非數(shù)字值

原生的isNaN會(huì)把參數(shù)轉(zhuǎn)換成數(shù)字(valueof)，而null、true、false以及長(zhǎng)度小于等于1的數(shù)組(元素為非NaN數(shù)據(jù))會(huì)被轉(zhuǎn)換成數(shù)字，這不是我想要的。Symbol類型的數(shù)據(jù)不具有valueof接口，所以isNaN會(huì)拋出錯(cuò)誤，這里放在后面，可避免錯(cuò)誤

function _isNaN(v){
    return !(typeof v === "string" || typeof v === "number") || isNaN(v)
}

37、max：求取數(shù)組中非NaN數(shù)據(jù)中的最大值

function max(arr){
    arr = arr.filter(item => !_isNaN(item))
    return arr.length ? Math.max.apply(null, arr) : undefined
}
//max([1, 2, "11", null, "fdf", []]) ==> 11

38、min：求取數(shù)組中非NaN數(shù)據(jù)中的最小值

function min(arr){
    arr = arr.filter(item => !_isNaN(item))
    return arr.length ? Math.min.apply(null, arr) : undefined
}
//min([1, 2, "11", null, "fdf", []]) ==> 1

39、random：返回一個(gè)lower - upper之間的隨機(jī)數(shù)

lower、upper無(wú)論正負(fù)與大小，但必須是非NaN的數(shù)據(jù)

function random(lower, upper){
    lower = +lower || 0
    upper = +upper || 0
    return Math.random() * (upper - lower) + lower;
}
//random(0, 0.5) ==> 0.3567039135734613
//random(2, 1) ===> 1.6718418553475423
//random(-2, -1) ==> -1.4474325452361945

40、Object.keys：返回一個(gè)由一個(gè)給定對(duì)象的自身可枚舉屬性組成的數(shù)組

Object.keys = Object.keys || function keys(object) {
    if(object === null || object === undefined){
        throw new TypeError("Cannot convert undefined or null to object");
    }
    let result = []
    if(isArrayLike(object) || isPlainObject(object)){
        for (let key in object) {
            object.hasOwnProperty(key) && ( result.push(key) )
        }
    }
    return result
}

41、Object.values：返回一個(gè)給定對(duì)象自身的所有可枚舉屬性值的數(shù)組

Object.values = Object.values || function values(object) {
    if(object === null || object === undefined){
        throw new TypeError("Cannot convert undefined or null to object");
    }
    let result = []
    if(isArrayLike(object) || isPlainObject(object)){
        for (let key in object) {
            object.hasOwnProperty(key) && ( result.push(object[key]) )
        }
    }
    return result
}

42、arr.fill：使用 value 值來(lái)填充 array，從start位置開(kāi)始, 到end位置結(jié)束（但不包含end位置），返回原數(shù)組

Array.prototype.fill = Array.prototype.fill || function fill(value, start, end) {
    let ctx = this
    let length = ctx.length;
    
    start = parseInt(start)
    if(isNaN(start)){
        start = 0
    }else if (start < 0) {
        start = -start > length ? 0 : (length + start);
      }
      
      end = parseInt(end)
      if(isNaN(end) || end > length){
          end = length
      }else if (end < 0) {
        end += length;
    }
    
    while (start < end) {
        ctx[start++] = value;
    }
    return ctx;
}
//Array(3).fill(2) ===> [2, 2, 2]

43、arr.includes：用來(lái)判斷一個(gè)數(shù)組是否包含一個(gè)指定的值，如果是返回 true，否則false，可指定開(kāi)始查詢的位置

Array.prototype.includes = Array.prototype.includes || function includes(value, start){
    let ctx = this
    let length = ctx.length;
    
    start = parseInt(start)
    if(isNaN(start)){
        start = 0
    }else if (start < 0) {
        start = -start > length ? 0 : (length + start);
      }
    
    let index = ctx.indexOf(value)
    
    return index >= start;
}

44、arr.find：返回?cái)?shù)組中通過(guò)測(cè)試（函數(shù)fn內(nèi)判斷）的第一個(gè)元素的值

Array.prototype.find = Array.prototype.find || function find(fn, ctx){
    fn = fn.bind(ctx)
    
    let result;
    this.some((value, index, arr), thisValue) => {
        return fn(value, index, arr) ? (result = value, true) : false
    })
    
    return result
}

45、arr.findIndex ：返回?cái)?shù)組中通過(guò)測(cè)試（函數(shù)fn內(nèi)判斷）的第一個(gè)元素的下標(biāo)

Array.prototype.findIndex = Array.prototype.findIndex || function findIndex(fn, ctx){
    fn = fn.bind(ctx)
    
    let result;
    this.some((value, index, arr), thisValue) => {
        return fn(value, index, arr) ? (result = index, true) : false
    })
    
    return result
}

46、performance.timing：利用performance.timing進(jìn)行性能分析

window.onload = function(){
    setTimeout(function(){
        let t = performance.timing
        console.log("DNS查詢耗時(shí) ：" + (t.domainLookupEnd - t.domainLookupStart).toFixed(0))
        console.log("TCP鏈接耗時(shí) ：" + (t.connectEnd - t.connectStart).toFixed(0))
        console.log("request請(qǐng)求耗時(shí) ：" + (t.responseEnd - t.responseStart).toFixed(0))
        console.log("解析dom樹(shù)耗時(shí) ：" + (t.domComplete - t.domInteractive).toFixed(0))
        console.log("白屏?xí)r間 ：" + (t.responseStart - t.navigationStart).toFixed(0))
        console.log("domready時(shí)間 ：" + (t.domContentLoadedEventEnd - t.navigationStart).toFixed(0))
        console.log("onload時(shí)間 ：" + (t.loadEventEnd - t.navigationStart).toFixed(0))

        if(t = performance.memory){
            console.log("js內(nèi)存使用占比 ：" + (t.usedJSHeapSize / t.totalJSHeapSize * 100).toFixed(2) + "%")
        }
    })
}

47、禁止某些鍵盤(pán)事件

document.addEventListener("keydown", function(event){
    return !(
        112 == event.keyCode || //F1
        123 == event.keyCode || //F12
        event.ctrlKey && 82 == event.keyCode || //ctrl + R
        event.ctrlKey && 78 == event.keyCode || //ctrl + N
        event.shiftKey && 121 == event.keyCode || //shift + F10
        event.altKey && 115 == event.keyCode || //alt + F4
        "A" == event.srcElement.tagName && event.shiftKey //shift + 點(diǎn)擊a標(biāo)簽
    ) || (event.returnValue = false)
});

48、禁止右鍵、選擇、復(fù)制

["contextmenu", "selectstart", "copy"].forEach(function(ev){
    document.addEventListener(ev, function(event){
        return event.returnValue = false
    })
});

github地址：https://github.com/hfhan/tools