Using spread operator to update an object value

Question

I have a function which adds a key to incoming object, but I have been told to use spread operator for that, I have been told that I can use the spread operator to create a

Answer 1

If you know the name of the property (a in the example below), then @crowder's answer is perfect:

const o3 = {...o1, a: "updated a"};
console.log(o3);

If the property name is in a variable, then you need to use Computed Property names syntax:

let variable = 'foo'
const o4 = {...o1, [variable]: "updated foo"};
console.log(o4);