js String对象的扩展函数

String.prototype.trim = function() {
   return this.replace(/^\s+|\s+$/g,"");
}
String.prototype.ltrim = function() {
   return this.replace(/^\s+/g,"");
}
String.prototype.rtrim = function() {
   return this.replace(/\s+$/g,"");
}
String.prototype.splitAndTrim = function($delimiter, $limit)
{
	var $ss = this.split($delimiter, $limit);
	for(var $i=0; $i<$ss.length; $i++)
		$ss[$i] = $ss[$i].trim();

	return $ss;
}
String.prototype.htmlEntities = function () {
   return this.replace(/&/g,'&amp;').replace(/</g,'&lt;').replace(/>/g,'&gt;');
}
String.prototype.stripTags = function () {
   return this.replace(/<([^>]+)>/g,'');
}
String.prototype.toArray = function() {
   return this.split('');
}
String.prototype.toIntArray = function() {
   var returnArray = [];
   for (var i=0; i<this.length; i++) {
      returnArray.push(this.charCodeAt(i));
   }
   return returnArray;
}
String.prototype.replaceAll = function($old, $snew){    
	return this.replace(new RegExp($old,"gm"),$snew);    
}
//变量替换var a = "I Love {0}, and You Love {1},Where are {0}!";a.format("You","Me");
String.prototype.format = function(){
    var args = arguments;
    return this.replace(/\{(\d+)\}/g,function(m,i,o,n){
        return args[i];
    });
}
//在字符串末尾追加字符串
String.prototype.append = function($str){
	return this.concat($str);
}
//删除指定索引位置的字符，索引无效将不删除任何字符
String.prototype.deleteCharAt = function($sIndex){
	if($sIndex<0 || $sIndex>=this.length){
		return this.valueOf();
	}else if($sIndex==0){
		return this.substring(1,this.length);
	}else if($sIndex==this.length-1){
		return this.substring(0,this.length-1);
	}else{
		return this.substring(0,$sIndex)+this.substring($sIndex+1);
	}
}
//删除指定索引间的字符串.$sIndex和$eIndex所在的字符不被删除！依赖deleteCharAt
String.prototype.deleteString = function($sIndex, $eIndex){
	if($sIndex==$eIndex){
		return this.deleteCharAt($sIndex);
	}else{
		if($sIndex>$eIndex){
			var tIndex=$eIndex;
			$eIndex=$sIndex;
			$sIndex=tIndex;
		}
		if($sIndex<0)$sIndex=0;
		if($eIndex>this.length-1)$eIndex=this.length-1;
		return this.substring(0,$sIndex+1)+this.substring($eIndex,this.length);
	}
}
//检查字符串是否以某个字符串(str)结尾
String.prototype.endsWith = function($str){
	return this.substr(this.length - $str.length) == $str;
}
//检查该字符串是否以某个字符串开始
String.prototype.startsWith = function(str){
	return this.substr(0, str.length) == str;
} 
//比较两个字符串是否相等，不区分大小写!
String.prototype.equalsIgnoreCase = function($str){
	if(this.length!=$str.length){
		return false;
	}else{
		var tmp1=this.toLowerCase();
		var tmp2=$str.toLowerCase();
		return tmp1==tmp2;
	}
}
//将指定的字符串插入到指定的位置后面!索引无效将直接追加到字符串的末尾
String.prototype.insert = function($ofset, $str){
	if($ofset<0 || $ofset>=this.length-1){
		return this.concat($str);
	}
	return this.substring(0,$ofset)+$str+this.substring($ofset+1);
}
//将指定的位置的字符设置为另外指定的字符或字符串.索引无效将直接返回不做任何处理！
String.prototype.setCharAt = function($ofset, $str){
	if($ofset<0 || $ofset>=this.length-1){
		return this.valueOf();
	}
	return this.substring(0,$ofset)+$str+this.substring($ofset+1);
}
String.prototype.replaceLen = function(start, len, replaced) {  
    if(!len)  
        return this;  

    if(start >= this.length)  
        return this;  

    var returnSeg = '';  
    var returnSeg2 = '';  
    var i = 0;  
    for (; i < this.length; i++){  
        var c = this.charAt(i);  
        if(i < start)  
            returnSeg += c;  

        if(i >= start + len)  
            returnSeg2 += c;  
    }  

    return returnSeg + replaced + returnSeg2;  
}  
/** 
 * 扩展基础类 
 * 替换字符，这个在替换填入比较有用，比如***天***小时 替换为 <input />天<input />小时 
 **/  
String.prototype.replaceChar = function(target, replaced, start) {  
    if(!target)  
        return this;  
    if(!start)  
        start = 0;  

    var returnVal = this.substring(0, start);  
    var index = 0;  
    for (var i = start; i < this.length; i++) {  
        var c = this.charAt(i);  
        target = typeof target == 'function' ? target.call(this, index) : target;  
        if (c == target) {  
            returnVal += typeof replaced == 'function' ? replaced.call(this, index) : replaced;  
            while (i < this.length - 1 && this.charAt(i + 1) == c) {  
                i++;  
            }  
            index++;  
        }else{  
            returnVal += c;  
        }  
    }  

    return returnVal;  
}  
//将该字符串反序排列
String.prototype.reverse = function(){
	var str="";
	for(var i=this.length-1;i>=0;i--){
		str=str.concat(this.charAt(i));
	}
	return str;
}
//计算长度，每个汉字占两个长度，英文字符每个占一个长度
String.prototype.ucLength = function(){
	var len = 0;
	for(var i=0;i<this.length;i++){
		if(this.charCodeAt(i)>255)len+=2;
		else len++;
	}
	return len;
}
//在字符串的左边填充一些特定的字符
String.prototype.lpad = function(len, s) {
	var a = new Array(this);
	var n = (len - this.length);
	for ( var i = 0; i < n; i++) {
		a.unshift(s);
	}
	return a.join("");
}
//在字符串的右边填充一些特定的字符
String.prototype.rpad = function(len, s) {
	var a = new Array(this);
	var n = (len - this.length);
	for ( var i = 0; i < n; i++) {
		a.push(s);
	}
	return a.join("");
}
//把字符串的首字母转化为大写
String.prototype.ucwords = function() {
	return this.substring(0,1).toUpperCase().concat(this.substring(1));
}
String.prototype.contains = function($str) {
	return this.indexOf($str) > -1 ? true : false;
}
//将格式为2008-04-02 10:08:44的字符串转成日期(String对象的值必须为: 2008-04-02 10:08:44)
String.prototype.toDate = function(){
	var str = this.replace(/-/g,"/");
	return (new Date(str));
}
//将原来用字符串表示的十进数转成十进制浮点数: precision为精度
String.prototype.toFloat = function(precision){
	precision = precision || 2;
	return parseFloat(this,10).toFixed(precision);
}
//将原来用字符串表示的十进数转成十进制整数
String.prototype.toInt = function(){
	return parseInt(this,10).toString();
}
//将两个原来用字符串表示的十进数相加后当作字串返回 : addend为加数
String.prototype.add = function(addend){
	var sum = parseFloat(this,10) + parseFloat(addend,10);
	return sum+"";
}
//十进制转其他进制代码如下nextScale为进制 如2,8,16
String.prototype.shiftScale = function(nextScale){
	return parseFloat(this).toString(nextScale);
}
/**
 * 各进制互相转换
 * this对象必须是整数
 * @param preScale 原是是几进制数
 * @param nextScale  要转换成几进制数
 */
String.prototype.scaleShift = function(preScale,nextScale){
	return parseInt(this,preScale).toString(nextScale);
}
//全角2半角 document.write("ＡＢＣ　１２３，我们都是好朋友");
String.prototype.dbc2sbc = function (){
	return this.replace(/[\uff01-\uff5e]/g,function(a){return String.fromCharCode(a.charCodeAt(0)-65248);}).replace(/\u3000/g," ");
}