JSFiddle - React, Tailwind, and code Playground

HTML

<img src="http://icons.iconarchive.com/icons/joseph-aeron/us-fish-and-wildlife-service/128/rabbit-icon.png" />

<img src="http://t3.gstatic.com/images?q=tbn:ANd9GcQ5-X9OgAVY41UGlDEEhy5txUL8BCy6cm_xMjWZsVxCJHECt1yGrllk4DdHeQ" />

CSS

img{vertical-align:middle }

JavaScript

small = parseInt($('img:eq(0)').css('height'));
big = parseInt($('img:eq(1)').width());

difference = big - small;
top_distance = difference/2;

alert(top_distance);
alert(big);