分享100個原生JavaScript技巧

　　首先在這裡要非常感謝無私分享作品的網友們，這些程式碼片段主要由網友們平時分享的作品程式碼裡面和經常去逛網站然後檢視原始檔收集到的。把平時網站上常用的一些實用功能程式碼片段通通收集起來，方便網友們學習使用，利用好的話可以加快網友們的開發速度，提高工作效率。

　　1、原生JavaScript實現字串長度擷取

function cutstr(str, len) {
    var temp;
    var icount = 0;
    var patrn = /[^\x00-\xff]/;
    var strre = "";
    for (var i = 0; i < str.length; i++) {
        if (icount < len - 1) {
            temp = str.substr(i, 1);
            if (patrn.exec(temp) == null) {
                icount = icount + 1
            } else {
                icount = icount + 2
            }
            strre += temp
        } else {
            break
        }
    }
    return strre + "..."
}

　　2、原生JavaScript獲取域名主機

function getHost(url) {
    var host = "null";
    if(typeof url == "undefined"|| null == url) {
        url = window.location.href;
    }
    var regex = /^\w+\:\/\/([^\/]*).*/;
    var match = url.match(regex);
    if(typeof match != "undefined" && null != match) {
        host = match[1];
    }
    return host;
}

　　3、原生JavaScript清除空格

String.prototype.trim = function() {
    var reExtraSpace = /^\s*(.*?)\s+$/;
    return this.replace(reExtraSpace, "$1")
}

　　4、原生JavaScript替換全部

String.prototype.replaceAll = function(s1, s2) {
    return this.replace(new RegExp(s1, "gm"), s2)
}

　　5、原生JavaScript轉義html標籤

function HtmlEncode(text) {
    return text.replace(/&/g, '&amp').replace(/\"/g, '&quot;').replace(/</g, '&lt;').replace(/>/g, '&gt;')
}

　　6、原生JavaScript還原html標籤

function HtmlDecode(text) {
    return text.replace(/&amp;/g, '&').replace(/&quot;/g, '\"').replace(/&lt;/g, '<').replace(/&gt;/g, '>')
}

　　7、原生JavaScript時間日期格式轉換

Date.prototype.Format = function(formatStr) {
    var str = formatStr;
    var Week = ['日', '一', '二', '三', '四', '五', '六'];
    str = str.replace(/yyyy|YYYY/, this.getFullYear());
    str = str.replace(/yy|YY/, (this.getYear() % 100) > 9 ? (this.getYear() % 100).toString() : '0' + (this.getYear() % 100));
    str = str.replace(/MM/, (this.getMonth() + 1) > 9 ? (this.getMonth() + 1).toString() : '0' + (this.getMonth() + 1));
    str = str.replace(/M/g, (this.getMonth() + 1));
    str = str.replace(/w|W/g, Week[this.getDay()]);
    str = str.replace(/dd|DD/, this.getDate() > 9 ? this.getDate().toString() : '0' + this.getDate());
    str = str.replace(/d|D/g, this.getDate());
    str = str.replace(/hh|HH/, this.getHours() > 9 ? this.getHours().toString() : '0' + this.getHours());
    str = str.replace(/h|H/g, this.getHours());
    str = str.replace(/mm/, this.getMinutes() > 9 ? this.getMinutes().toString() : '0' + this.getMinutes());
    str = str.replace(/m/g, this.getMinutes());
    str = str.replace(/ss|SS/, this.getSeconds() > 9 ? this.getSeconds().toString() : '0' + this.getSeconds());
    str = str.replace(/s|S/g, this.getSeconds());
    return str
}

　　8、原生JavaScript判斷是否為數字型別

function isDigit(value) {
    var patrn = /^[0-9]*$/;
    if (patrn.exec(value) == null || value == "") {
        return false
    } else {
        return true
    }
}

　　9、原生JavaScript設定cookie值

function setCookie(name, value, Hours) {
    var d = new Date();
    var offset = 8;
    var utc = d.getTime() + (d.getTimezoneOffset() * 60000);
    var nd = utc + (3600000 * offset);
    var exp = new Date(nd);
    exp.setTime(exp.getTime() + Hours * 60 * 60 * 1000);
    document.cookie = name + "=" + escape(value) + ";path=/;expires=" + exp.toGMTString() + ";domain=360doc.com;"
}

　　10、原生JavaScript獲取cookie值

function getCookie(name) {
    var arr = document.cookie.match(new RegExp("(^| )" + name + "=([^;]*)(;|$)"));
    if (arr != null) return unescape(arr[2]);
    return null
}