Add an object key assigment from variable (faster way)

[technic404]

We want to pass a key to an object that is assigned to variable.

Instead of doing

const key = "b";
const obj = { 
    a: 1
};

obj[key] = "value";

We can define the object key without obj[key]

const key = "b";
const obj = { 
    a: 1, 
    [key]: "value"
};