//-------------------- util.js
function trim(strValue) {
	if( strValue.length == 0) 
		return ("");
		
   	strValue = strValue.replace(/^( )*|( )*$/ig,"");
   	return strValue;	
}

String.prototype.strLen = function() {
    var len = 0;
    for (var i = 0; i < this.length; i++) {
      if (this.charCodeAt(i) > 255 || this.charCodeAt(i) < 0) {
        len += 2; 
      }
      else {
        len ++;
      } 
    }
    return len;
}

//将字符串拆成字符，并存到数组中
String.prototype.strToChars = function(){
    var chars = new Array();
    for (var i = 0; i < this.length; i++){
      chars[i] = [this.substr(i, 1), this.isCHS(i)];
    }
    String.prototype.charsArray = chars;
    return chars;
}
 
//判断某个字符是否是汉字
String.prototype.isCHS = function(i){
     if (this.charCodeAt(i) > 255 || this.charCodeAt(i) < 0) {
       return true;
     }  
     else {
       return false;
     }
         
 }
//截取字符串（从start字节到end字节）
String.prototype.subCHString = function(start, end){
    var len = 0;
    var str = "";
    this.strToChars();
    for (var i = 0; i < this.length; i++) {
      if (this.charsArray[i][1]) {
        len += 2;
      }
      else {
        len++;
      }
      if (end < len) {
        return str;
      }
      else if (start < len) {
        str += this.charsArray[i][0];
      }
    }
    return str;
}
//截取字符串（从start字节截取length个字节）
String.prototype.subCHStr = function(start, length){
    return this.subCHString(start, start + length);
}