js常用工具函数汇总

下面给大家梳理了我平时在工作中常用的js方法，本来是打算作为自己的工具库的，为了发现代码的最佳方案，再此贴出，望相互交流。

程序员必读

Css3编码技巧

1.检测平台（设备）类型

var isWechat = /micromessenger/i.test(navigator.userAgent),
    isWeibo = /weibo/i.test(navigator.userAgent),
    isQQ = /qq\//i.test(navigator.userAgent),
    isIOS = /(iphone|ipod|ipad|ios)/i.test(navigator.userAgent),
    isAndroid = /android/i.test(navigator.userAgent);

2.时间格式化

// 时间格式化
function format_date(timeStamp) {
    var date = new Date(timeStamp);
    return date.getFullYear() + "年"
        + prefix_zero(date.getMonth() + 1) + "月"
        + prefix_zero(date.getDate()) + "日 "
        + prefix_zero(date.getHours()) + ":"
        + prefix_zero(date.getMinutes());
}
// 数字格式化
function prefix_zero(num) {
    return num >= 10 ? num : "0" + num;
}

3.倒计时函数

// 倒计时时间格式化
function format_time(timeStamp) {
    var day = Math.floor(timeStamp / (24 * 3600 * 1000));
    var leave1 = timeStamp % (24 * 3600 * 1000);
    var hours = Math.floor(leave1 / (3600 * 1000));
    var leave2 = leave1 % (3600 * 1000);
    var minutes = Math.floor(leave2 / (60 * 1000));
    var leave3 = leave2 % (60 * 1000);
    var seconds = Math.floor(leave3 / 1000);
    if (day) return day + "天" + hours + "小时" + minutes + "分";
    if (hours) return hours + "小时" + minutes + "分" + seconds + "秒";
    if (minutes) return minutes + "分" + seconds + "秒";
    if (seconds) return seconds + "秒";
    return "时间到！";
}

4.判断设备是否支持触摸事件

var isSupportTouch = ("ontouchstart" in document.documentElement) ? true : false;

5.js+rem实现移动端适配

(function (doc, win) {
    var docEl = doc.documentElement,
        resizeEvt = 'orientationchange' in window ? 'orientationchange' : 'resize',
        recalc = function () {
            var clientWidth = docEl.clientWidth;
            var fontSize = 20;
            docEl.style.fontSize = fontSize + 'px';
            var docStyles = getComputedStyle(docEl);
            var realFontSize = parseFloat(docStyles.fontSize);
            var scale = realFontSize / fontSize;
            console.log("realFontSize: " + realFontSize + ", scale: " + scale);
            fontSize = clientWidth / 667 * 20;
            if(isIphoneX()) fontSize = 19;
            fontSize = fontSize / scale;
            docEl.style.fontSize = fontSize + 'px';
        };
    // Abort if browser does not support addEventListener
    if (!doc.addEventListener) return;
    win.addEventListener(resizeEvt, recalc, false);
    doc.addEventListener('DOMContentLoaded', recalc, false);

    // iphoneX判断
    function isIphoneX(){
        return /iphone/gi.test(navigator.userAgent) && (screen.height == 812 && screen.width == 375)
    }

})(document, window);

6.检查是否为中文

let isCN = (str) => { return /^[\u4e00-\u9fa5]*$/.test(str) }

7.禁用enter表单自动提交

//禁用Enter键表单自动提交
        document.onkeydown = function(event) {
            var target, code, tag;
            if (!event) {
                event = window.event; //针对ie浏览器
                target = event.srcElement;
                code = event.keyCode;
                if (code == 13) {
                    tag = target.tagName;
                    if (tag == "TEXTAREA") { return true; }
                    else { return false; }
                }
            }
            else {
                target = event.target; //针对遵循w3c标准的浏览器，如Firefox
                code = event.keyCode;
                if (code == 13) {
                    tag = target.tagName;
                    if (tag == "INPUT") { return false; }
                    else { return true; }
                }
            }
        };

8.敏感符号转义

function entities(s) {
    let e = {
        '"': '"',
        '&': '&',
        '<': '&lt;',
        '>': '&gt;'
    }
    return s.replace(/["<>&]/g, m => {
        return e[m]
    })
}