code: function(fn, suffix) {
  	if(suffix.charAt(0) !== '.') {
  		suffix = '.' + suffix;
  	}
  	
  	if(fn.length <= suffix.length) {
  		return false;
  	}
  	
  	var str = fn.substring(fn.length - suffix.length).toLowerCase();
  	suffix = suffix.toLowerCase();
  	return str === suffix;
  }
docs: Check file suffix
  
  @param fn {String} file name
  @param suffix {String} suffix string, such as .js, etc.