$('.selector').miniParallax();

// or 

$('.selector').miniParallax({
    speed: 0.3
});

bower install mini-parallax --save-dev

speed: 0.5

1 means parallax element will scroll in the same speed of browser scroll 0.5 means element will scroll 50% slower than browser scroll

<div class="parallax">Suppose it has background image and we want to add parallax effect on it.</div>

So JS will be -

$('.parallax').miniParallax();

Another way is -

<section class="selector" data-parallax-item=".parallax">
    <figure><img class="parallax" src="images/2.jpg" alt=""></figure>
</section>

Now when selector section will come in view-port, then image will have parallax behavior. Now js will look like -

$('.selector').miniParallax();

You may notice data attribute data-parallax-item and it's value .parallax that means parallax behavior will be add to .parallax item when the viewport is .selector

http://habibhadi.com/lab/mini-parallax/