How do I create a dynamic key to be added to a JavaScript object variable

js-dynamic-keys.md

If you're able to use ES6 JavaScript features, you can use Computed Property Names to handle this very easily:

var key = 'DYNAMIC_KEY',
obj = {
  [key]: 'ES6!'
};

console.log(obj);
// > { 'DYNAMIC_KEY': 'ES6!' }

Source: https://stackoverflow.com/a/2462810/6456709