Create array and push into it in one line

Question

The following is just a theoretical JavaScript question. I am curious if the following can be converting into a single statement:

if(!window.foo){
  window.foo =         


        

Answer 1

Your code works just fine if you add parentheses so that it does what you intended:

(window.foo || (window.foo = [])).push('bar');

Without the parentheses, it thinks that it should evaluate window.foo || window.foo first, and then assign the array to the result of that, which is not possible.