Computed property names. Any expression whose value can convert to a string or symbol will work. ES6 added them: https://developer.mozilla.org/en-US/docs/Web/J

Computed property names. Any expression whose value can convert to a string or symbol will work. ES6 added them: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Object_initializer#Computed_property_names https://developer.mozilla.org/en-US/docs/Web/JavaScript/Refe...