enhance.helper.js

// Plain text URL to anchor tags Handlebars Helper

(function(){
    // defines markup enhancement regex
    var protocol = /(\b(https?|ftp):\/\/[-A-Z0-9+&@#\/%?=~_|!:,.;]*[-A-Z0-9+&@#\/%=~_|])/gim
      , scheme   = /(^|[^\/])(www\.[\S]+(\b|$))/gim;
			
    /*
     * Registers a Helper method with handlebars which, given a string of
     * plain text or existing markup, provides enhancements of plain text 
     * URLs, converting them to their respective anchor tag equivilents.=
     */
    Handlebars.registerHelper('enhance', function(text) {
	text = text.replace( protocol, '<a href="$1" target="_blank">$1</a>');
	text = text.replace( scheme,   '$1<a href="http://$2" target="_blank">$2</a>' );
	return new Handlebars.SafeString( text );
    });
}());

enhance.helper.spec.js

// Plain text URL to anchor tags Handlebars Helper Spec

describe( 'Handlebars Helpers', function() {
    // define a reference to the underlying helpers object.
    var helpers = Handlebars.helpers
      , enhance = helpers.enhance;
	
    describe( 'The "enhance" markup helper', function() {
        it ( 'should be registered', function() {
            expect( enhance ).toBeDefined();
        });
        
        it ( 'should return a Handlebars.SafeString', function() {
            expect( enhance( "some text" ) instanceof Handlebars.SafeString).toBeTruthy();
        });
        
        it ( 'should preserve existing markup', function() {
            var expected = '<strong>Some unescaped markup</strong> and a <a href="#">link</a>';
            var actual   = enhance( expected ).string;
            expect( actual ).toEqual( expected );
        });
        
        it ( 'should replace URLs with anchor tags', function() {
            var actual = enhance( 'Some text with a link http://www.ericfeminella.com' );
            expect( actual.string ).toEqual( 'Some text with a link <a href="http://www.ericfeminella.com" target="_blank">http://www.ericfeminella.com</a>' );
        });
    })
});