JSFiddle - React, Tailwind, and code Playground

JavaScript

function mutatePassReferenceByValue(obj) {
  obj.a = true;
}
function mutatePassByReference(obj) {
  obj = {a: true};
}

var obj = {a: false};
mutatePassByReference(obj)
console.log(obj.a); // prints false, would print true is javascrip was pass-by-reference
mutatePassReferenceByValue(obj)
console.log(obj.a); // prints true