placeholder.js

$.fn.placeholder = function(text){
  if(typeof text !== 'undefined'){
		this.attr('data-placeholder', text);
	} else {
		return this.attr('data-placeholder');
	}
	var that = $(this)
	if(that.val('')){
		that.val(text);
	}
	that.focus(function(){
		if($(this).val() === text)
		{
			that.val('')
		}
	}).blur(function(){
		if(that.val() === ''){
			that.val(text)
		}
	})
	return that;
}

// example
var $fn = $('#first_name');
$fn.placeholder('First Name');

$('#form').submit(function(){
	if($fn.val() === $fn.placeholder()){
		return false;
	}
})