常用的javascript函数

1.字符串长度截取
function cutstr(str, len) {
var temp,
icount = 0,
patrn = /[^\x00-\xff]/，
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.替换全部
String.prototype.replaceAll = function(s1, s2) {
return this.replace(new RegExp(s1, "gm"), s2)
}


3.清除空格
String.prototype.trim = function() {
var reExtraSpace = /^\s*(.*?)\s+$/;




4清除左空格/右空格
function ltrim(s){ return s.replace( /^(\s*|*)/, ""); }
function rtrim(s){ return s.replace( /(\s*|*)$/, ""); }


5判断是否以某个字符串开头
String.prototype.startWith = function (s) {
return this.indexOf(s) == 0
}




6判断是否以某个字符串结束
String.prototype.endWith = function (s) {
var d = this.length - s.length;
return (d >= 0 && this.lastIndexOf(s) == d)
}




7转义html标签
function HtmlEncode(text) {
return text.replace(/&/g, '&').replace(/\"/g, '"').replace(//g, '>')
}




-8、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(/m m/, 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
}




9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
}
}




10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() + ";"
}


12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")
}
}
}






13设为首页
function setHomepage() {
if (document.all) {
document.body.style.behavior = 'url(#default#homepage)';
document.body.setHomePage('http://www.baidu.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.baidu.com')
}
}