JavaScript常用工具函数大全

1. Set的简单实现

function set(v) {
        function unique(arr) {
            let ret = [];
            let obj = {};
            arr.forEach(item => {
                if(!obj[item]) {
                    obj[item] = true;
                    ret.push(item);
                }
            });
            return ret;
        }
        function SetRe(arr) {
            this.items = arr ? unique(arr) : [];
            this.size = arr.length;
        }
        SetRe.prototype = {
            has: function(v) {
                return this.items.some(item => item === v);
            },
            add: function(v) {
                this.items.push(v);
                this.size++;
            },
            remote: function(v) {
                return this.items.some((item, index) => {
                    if(item === v) {
                        this.items.splice(index, 1);
                        this.size = 0;
                        return true;
                    }
                    return false;
                })
            },
            clear: function() {
                this.items = [];
                this.size = 0;
            },
            getValues: function() {
                return this.items
            }
        }
    }

2. 生成一个重复的字符串，有n个str组成，可修改为填充为数组等 OR str.repeat(次数2)

function repeat(str, n) {
    let res = '';
    while(n) {
        if(n % 2 === 1) {
            res += str;
        }
        if(n > 1) {
            str += str;
        }
        n >>= 1;
    }
    return res;
}

3. 格式化时间

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)
}

4. 将指定字符串由一种时间格式转化为另一种

function dateStrForma(str, from, to) { 
    str += '';
    let Y = '';
    if((Y = from.indexOf('YYYY')) >= 0){
        Y = str.substr(Y, 4);
        to = to.replace(/YYYY|yyyy/g, Y);
    } else if((Y = from.indexOf('YY')) >= 0) {
        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;

5. 根据字符串路径获取对象属性 : ‘obj[0].count’

function getPropByPath(obj, path, strict) { 
    let tempObj = obj;
    path = path.replace(/[(\w+)]/g, '.$1'); //将[0]转化为.0
    path = path.replace(/^\./, ''); //去除开头的.
    let keyArr = path.split('.'); //根据.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) {//开启严格模式，没找到对应key值，抛出错误
                throw new Error('please transfer a valid prop path to form item!');
            }
            break;
        }
    }
    return {
        o: tempObj, //原始数据
        k: keyArr[i], //key值
        v: tempObj ? tempObj[keyArr[i]] : null // key值对应的值
    };
}

6. 检测数据是不是基本数据类型

function isStatic(v) {
	return(
		typeof v === 'string' ||
        typeof value === 'number' ||
        typeof value === 'boolean' ||
        typeof value === 'undefined' ||
        typeof value === 'symbol'
	)
}

7. 判断数据是不是引用数据类型

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

8. 判断数据是不是数组

function isArray(v) { 
	return (
		v instanceof Array ||
		Array.isArray(v) ||
		Object.prototype.toString.call(v) === '[object Array]'
	)
}

9. 检测数据是什么类型

function isType(value) { 
	let type = Object.prototype.toString.call(value);
	switch (type) {
        case "[object String]":
            return "字符串";
        case "[object Number]":
            return "数字";
        case "[object Boolean]":
            return "布尔";
        case "[object Function]":
            return "函数";
        case "[object Array]":
            return "数组";
        case "[object Object]":
            return "对象";
        case "[object Date]":
            return "日期";
        case "[object RegExp]":
            return "正则";
        case "[object Math]":
            return "数学对象";
        case "[object Undefined]":
            return "未定义";
        case "[object Null]":
            return "空";
    }
}

10. 返回 值的类型

function getRawType(v) { 
	return Object.prototype.toString.call(v).slice(8, -1);
}

11. 判断是否为浏览器内置函数 内置函数toString后的主体代码块为 [native code] ，而非内置函数则为相关代码

function isNative(v) { 
	return typeof v === 'function' && (/native code/.test(v.tiString()));
}

12. 判断是否为null

function isEmpty(v) {
	if(v == null) return null;
	if(Object.prototype.toString.call(value) === '[object Array]') return v.length;
	if(Object.prototype.toString.call(value) === '[object Object]') { 
		for(let k in v) {
			if(v.hasOwnProperty(k)) return false;
		}
	}
}

13. 检查数据是否是非数字值

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

14. 求取数组中最大值 最小值

function maxOrMin(arr){ 
    arr.sort(function (a, b) { 
        return a-b; //return < 0 a在b之前 > 0 b在a之前
    });
    Math.max(arr);
    Math.min(arr);
    return arr[arr.length-1];
}

15. 返回一个lower - upper之间的随机数

function random(lower, upper){
    lower = +lower || 0
    upper = +upper || 0
    return Math.random() * (upper - lower) + lower;
}

16. 禁止某些键盘事件

function keydown() {
    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 + 点击a标签
        ) || (event.returnValue = false)
    });
}

17. 禁止右键、选择、复制

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

18. 记忆函数：通过闭包缓存函数的运算结果

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

19. _命名替换为驼峰命名

function camelize(str) { 
	return str.replace(/_(\w)/g, function(z, a, b) {
		return a ? a.toUpperCase() : '';
	})
}

20. 驼峰命名转_命名

function hump(v) {
        return v.replace(/\B[A-Z]/g, function(z) {
            return z ? '_' + z.toLowerCase() : '';
        }); ||
        return v.replace(/\B([A-Z])/g, '_$1').toLowerCase();
    }

21. 字符串首位大写

function capitalize(str) {
    return str.charAt(0).toUpperCase() + str.slice(1)
}

22. 将属性混合到目标对象中

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

23. 识别各种浏览器及平台 Navigator

function getBrowser() {
    let inBrowser = typeof window !== 'undefined'; //运行环境是浏览器
    //运行环境是微信
    let inWeex = typeof WXEnvironment !== 'undefined' && !!WXEnvironment.platform;
    let weexPlatform = inWeex && WXEnvironment.platform.toLowerCase();
    //浏览器 UA 判断
    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;
}

24. 获取浏览器信息

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
    }
}

25. 检测是否为PC端浏览器模式

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)
}

26. 获取Url参数，返回一个对象

function GetUrlParam(url) { 
    url = url ? 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;
}

27. 按“F11”

function isFullscreenForNoScroll(){
    let explorer = window.navigator.userAgent.toLowerCase();
    if(explorer.indexOf('chrome')>0){//webkit
        if (document.body.scrollHeight === window.screen.height && document.body.scrollWidth === window.screen.width) {
            alert("全屏");
        } else {
            alert("不全屏");
        }
    }else{//IE 9+  fireFox
        if (window.outerHeight === window.screen.height && window.outerWidth === window.screen.width) {
            alert("全屏");
        } else {
            alert("不全屏");
        }
    }
}

28. 退出全屏

function exitFullscreen(){
    let elem = parent.document;
    elem.webkitCancelFullScreen
        ? elem.webkitCancelFullScreen()
        : elem.mozCancelFullScreen
        ? elem.mozCancelFullScreen()
        : elem.cancelFullScreen
            ? elem.cancelFullScreen()
            : elem.msExitFullscreen
                ? elem.msExitFullscreen()
                : elem.exitFullscreen
                    ? elem.exitFullscreen()
                    : alert("切换失败,可尝试Esc退出");
}