Comment by chaorace

To go maximum pedant here, I want to say that you're somewhat conflating syntax improvements for stylistic shifts. Pre ES6 JS still allows for FP programming, so a more fair approximation of the Pre-ES6 code would be...

  var increment = [1, 2, 3, 4, 5].map( function(num){ return num + 1 } )

The two big syntactic wins of modern JS are let/const over the filth that was var and the convenience of arrow functions over anonymous function literals.