Javascript String startWith(str)

String.prototype.startWith = function(str) {
  var reg = new RegExp("^" + str);
  return reg.test(this);
};

String.prototype.startWith = function(str){
  return this.indexOf(str) == 0;
};

String.prototype.startWith=function(str){
    if(str==null||str==""||this.length==0||str.length>this.length)
        return false;
    if(this.substr(0,str.length)==str)
        return true;
    else/*from w  w  w .  j  ava  2s. c o m*/
        return false;
    return true;
}

String.prototype.startWith = function(str) {
 var result = true;
 if (typeof(str)=='string' && str.length <= this.length) {
  for (var i=0,len=str.length;i<len;i++) {
   if (str.charAt(i) == this.charAt(i)) {
    continue;//from   w  ww .ja va  2 s .  c om
   } else {
    result = false;
    break;
   }
  }
 } else {
  result = false;
 }
 return result;
}

String.prototype.startWith = function(str) {
  return (this.match("^" + RegExp.escape(str))==str);
}