How to get current index in Array prototype map?

Question

I\'m using Array.prototype.map.call to store in an array a bunch of node list objects:

function getListings() {
    return Array.prototype.map.call(document.         


        

Answer 1

The MDN documentation says:

callback is invoked with three arguments: the value of the element, the index of the element, and the Array object being traversed.

So

function getListings() {
    return Array.prototype.map.call(document.querySelectorAll('li.g'), function(e, rank) { // magic 
         return {
             rectangle: e.getBoundingClientRect(),
             rank: rank // <-- magic happens
         }
    }
}