Test migration to jest by hand

Apparently using regular expressions is way easier.

test/on/on.js

@@ -0,0 +1,6 @@
+const on = (el, evt, fn, opts = {}) => {
+const delegatorFn = e => e.target.matches(opts.target) && fn.call(e.target, e);
+el.addEventListener(evt, opts.target ? delegatorFn : fn, opts.options || false);
+if (opts.target) return delegatorFn;
+};
+module.exports = on;