100个原生JavaScript技巧大收集（一）

在本系列文章中，我们将陆续分享一些原生JavaScript技巧，希望对学习JS的朋友有所帮助。

1、原生JavaScript实现字符串长度截取

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获取域名主机

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替换全部

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

5、原生JavaScript转义html标签

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

6、原生JavaScript还原html标签

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

7、原生JavaScript时间日期格式转换

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判断是否为数字类型

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

9、原生JavaScript设置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获取cookie值

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

11、原生JavaScript加入收藏夹

function AddFavorite(sURL, sTitle) { 
    try { 
        window.external.addFavorite(sURL, sTitle) 
    } catch(e) { 
        try { 
            window.sidebar.addPanel(sTitle, sURL, "") 
        } catch(e) { 
            alert("加入收藏失败，请使用Ctrl+D进行添加") 
        } 
    } 
} 

12、原生JavaScript设为首页

function setHomepage() { 
    if (document.all) { 
        document.body.style.behavior = 'url(#default#homepage)'; 
        document.body.setHomePage('http://www.jq-school.com') 
    } else if (window.sidebar) { 
        if (window.netscape) { 
            try { 
                netscape.security.PrivilegeManager.enablePrivilege("UniversalXPConnect") 
            } catch(e) { 
                alert("该操作被浏览器拒绝，如果想启用该功能，请在地址栏内输入 about:config,然后将项 signed.applets.codebase_principal_support 值该为true") 
            } 
        } 
        var prefs = Components.classes['@mozilla.org/preferences-service;1'].getService(Components.interfaces.nsIPrefBranch); 
        prefs.setCharPref('browser.startup.homepage', 'http://www.jq-school.com') 
    } 
} 

13、原生JavaScript判断IE6

var ua = navigator.userAgent.toLowerCase(); 
var isIE6 = ua.indexOf("msie 6") > -1; 
if (isIE6) { 
    try { 
        document.execCommand("BackgroundImageCache", false, true) 
    } catch(e) {} 
} 

14、原生JavaScript加载样式文件

function LoadStyle(url) { 
    try { 
        document.createStyleSheet(url) 
    } catch(e) { 
        var cssLink = document.createElement('link'); 
        cssLink.rel = 'stylesheet'; 
        cssLink.type = 'text/css'; 
        cssLink.href = url; 
        var head = document.getElementsByTagName('head')[0]; 
        head.appendChild(cssLink) 
    } 
} 

15、原生JavaScript返回脚本内容

function evalscript(s) { 
        if(s.indexOf('<script') == -1) return s; 
        var p = /<script[^\>]*?>([^\x00]*?)<\/script>/ig; 
        var arr = []; 
        while(arr = p.exec(s)) { 
                var p1 = /<script[^\>]*?src=\"([^\>]*?)\"[^\>]*?(reload=\"1\")?(?:charset=\"([\w\-]+?)\")?><\/script>/i; 
                var arr1 = []; 
                arr1 = p1.exec(arr[0]); 
                if(arr1) { 
                        appendscript(arr1[1], '', arr1[2], arr1[3]); 
                } else { 
                        p1 = /<script(.*?)>([^\x00]+?)<\/script>/i; 
                        arr1 = p1.exec(arr[0]); 
                        appendscript('', arr1[2], arr1[1].indexOf('reload=') != -1); 
                } 
        } 
        return s; 
} 

16、原生JavaScript清除脚本内容

function stripscript(s) { 
        return s.replace(/<script.*?>.*?<\/script>/ig, ''); 
} 

17、原生JavaScript动态加载脚本文件

function appendscript(src, text, reload, charset) { 
        var id = hash(src + text); 
        if(!reload && in_array(id, evalscripts)) return; 
        if(reload && $(id)) { 
                $(id).parentNode.removeChild($(id)); 
        } 

        evalscripts.push(id); 
        var scriptNode = document.createElement("script"); 
        scriptNode.type = "text/javascript"; 
        scriptNode.id = id; 
        scriptNode.charset = charset ? charset : (BROWSER.firefox ? document.characterSet : document.charset); 
        try { 
                if(src) { 
                        scriptNode.src = src; 
                        scriptNode.onloadDone = false; 
                        scriptNode.onload = function () { 
                                scriptNode.onloadDone = true; 
                                JSLOADED[src] = 1; 
                        }; 
                        scriptNode.onreadystatechange = function () { 
                                if((scriptNode.readyState == 'loaded' || scriptNode.readyState == 'complete') && !scriptNode.onloadDone) { 
                                        scriptNode.onloadDone = true; 
                                        JSLOADED[src] = 1; 
                                } 
                        }; 
                } else if(text){ 
                        scriptNode.text = text; 
                } 
                document.getElementsByTagName('head')[0].appendChild(scriptNode); 
        } catch(e) {} 
} 

18、原生JavaScript返回按ID检索的元素对象

function $(id) { 
        return !id ? null : document.getElementById(id); 
} 

19、原生JavaScript返回浏览器版本内容

function browserVersion(types) { 
        var other = 1; 
        for(i in types) { 
                var v = types<i> ? types<i> : i; 
                if(USERAGENT.indexOf(v) != -1) { 
                        var re = new RegExp(v + '(\\/|\\s)([\\d\\.]+)', 'ig'); 
                        var matches = re.exec(USERAGENT); 
                        var ver = matches != null ? matches[2] : 0; 
                        other = ver !== 0 && v != 'mozilla' ? 0 : other; 
                }else { 
                        var ver = 0; 
                } 
                eval('BROWSER.' + i + '= ver'); 
        } 
        BROWSER.other = other; 
} 

20、原生JavaScript元素显示的通用方法

function $(id) { 
        return !id ? null : document.getElementById(id); 
} 
function display(id) { 
        var obj = $(id); 
        if(obj.style.visibility) { 
                obj.style.visibility = obj.style.visibility == 'visible' ? 'hidden' : 'visible'; 
        } else { 
                obj.style.display = obj.style.display == '' ? 'none' : ''; 
        } 
} 

文章源自：http://www.jq-school.com/Show.aspx?id=300