JSFiddle - React, Tailwind, and code Playground
HTML
<div id='output1'></div>
<div id='output2'></div>
JavaScript
var foo = function() {
var that = {
a: 7,
b: 6
};
that.c = that.a + that.b;
return that;
}(); // notice that this line executes foo
foo; // foo can be used without an instantiation call
document.getElementById('output1').innerText = foo.c; //13
foo.c = 14; // c is writable
document.getElementById('output2').innerText = foo.c; //14