ES6 array differenceBy
by Julien Roche
HTML
<pre></pre>
Babel + JSX
let a = new Set([{ 'x': 2 }, { 'x': 1 }]);
let b = new Set([{ 'x': 1 }]);
let differenceBy = [...a].filter(item => b.has(x));
document.querySelector('pre').innerHTML = JSON.stringify(differenceBy, null, 3);