JSFiddle - React, Tailwind, and code Playground

JavaScript

var a;

function wrap(val) {
    return {val:val};
}

function foo() {
    this.val+=10;
}

a=function(obj) {
    a=foo.bind(obj);
}

var p=wrap(7);
a(p);
alert("Before: " + p.val);
a();
alert("After: " + p.val);