Find character and wrap the word(s) containing it

wordWrap.js

/**
*
* Verifica si existe la funcion, sino la crea (solo existe en firefox)
*
**/
if(!('contains' in String.prototype)){
	String.prototype.contains = function( str, startIndex ) {
		return -1 !== String.prototype.indexOf.call( this, str, startIndex );
	};
};

/*
*
* Find character and wrap the word(s) containing it
*
* @params character 		- string
* @params tag 				- string, nombre de etiqueta html
*
**/
String.prototype.wrapp = function( character, tag ) {
	var text = "", split = this.split( " " );
	for( var i = 0; i <= split.length - 1; i++ ) {
		if( split[ i ].contains( character ) ){
			split[ i ] = "<" + tag + ">" + split[ i ] + "</" + tag + ">";
		};
		text = text + split[ i ] + " ";
	};
	return text;
};

var text = "this #is a text";
text = text.wrapp( "#", "span" ); //this <span>#is</span> a text"