how to update specific key value of object in js code example

Example: update a certain key in dictionary javascript

const target = {c: 4, d: 5}
const source = {a: 1, b: 2, c: 3};

const newObj = Object.assign({}, target, source);

console.log(newObj); //=> {a: 1, b: 2, c: 3, d: 5}