100个直接可以拿来用的JavaScript实用功能

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, '"').replace(//g, '>')
   }

6、原生JavaScript还原html标签

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