Default value filter for Angular JS applications - allows you to output a variable, and assign it a default value if it has a value of 0, null, or is an empty string. Very similar to PHP's empty() function, but provides a default value instead of a boolean.

filters.js

/**
 * Sets a default value for a given input.
 *
 * @param mixed input
 * @param string defaultValue
 * @return string
 */
module.filter( 'default', [ '$filter', function( $filter ) {
	return function( input, defaultValue ) {
		if ( !input ) return defaultValue;
		
		return input;
	};
}]);

Why you inject $filter while you do not need it?

return !input ? defaultValue : input;