Use the power of slick.js in fullscreen mode.
1. Include slick-fullscreen.js and slick-fullscreen.css in your project.
2. Add data-slick-fullscreen to the container you want to open images in fullscreen.
<section data-slick-fullscreen>
<a href="image1.jpg">
<img src="image1-thumb.jpg">
</a>
<a href="image2.jpg">
<img src="image2-thumb.jpg">
</a>
</section>
By default all anchor tags are picked and used for the images, you can customise a different target by changing target along with any other options slick provides.
<section data-slick-fullscreen='{"target": "img", "slick":{ "dots": true, "centerMode": true, "centerPadding": "60px"}}'>
<img src="image1.jpg">
<img src="image2.jpg">
</section>