String.E = "";

String.isSet = function(str) {
	return((str!=null)&&(str.length!=0));
}

String.prototype.isEmpty = function() {
	return(this.length == 0);
}

String.prototype.startsWith = function(str,ci) {
	if(this.length<str.length) return false;
	if((arguments.length > 1) && ci) {
		return(this.substr(0,str.length).toUpperCase() == str.toUpperCase());	
	}
	return(this.substr(0,str.length) == str);
}

String.prototype.endsWith = function(str,ci) {
	if(this.length < str.length) return false;
	var i = (this.length - str.length);
	if((arguments.length > 1) && ci) {
		return(this.substr(i).toUpperCase() == str.toUpperCase());	
	}
	return(this.substr(i) == str);
}

String.prototype.trim = function() {
	var from = 0;
	var to = this.length;
	for(var i=0;i<this.length;++i) {
		var c = this.charAt(i);
		if((c==' ')||(c=='\n')||(c=='\t')||(c=='\r')) {
			++from;
		} else {
			break;
		}
	}
	for(var i=(this.length-1);i>from;--i) {
		var c = this.charAt(i);
		if((c==' ')||(c=='\n')||(c=='\t')||(c=='\r')) {
			--to;
		} else {
			break;
		}
	}
	return this.substring(from,to);
}