String.prototype.trim = function()
	{
		return this.replace(/^\s+/,'').replace(/\s+$/,'');
	}



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



	String.prototype.isNull = function()
	{
		return (this == null);
	}



	String.prototype.leftChar = function(vi_number, vi_digits, vs_char)
	{
		var ls_number = new String(vi_number);
		if (vs_char.length > 1) vs_char = vs_char.substr(0, 1)
		if (ls_number.length < vi_digits)
		{
			var ls_left = '';
			for (var li_char = 0; li_char < (vi_digits - ls_number.length); li_char++) ls_left += vs_char;
			ls_number = ls_left + ls_number;
		}
		return ls_number;
	}