why Array.prototype.map.call instead of Array.map.call

Question

I fell upon some lines of code where the guy uses Array.prototype.map.call instead of Array.map.call:

function getLinks() {
    va         


        

Answer 1

Because Array.map.call doesn't work. Array.map is built to accept two parameters: the array, and the callback. call runs a function setting its this to the object you supply.

So, when you run Array.prototype.map.call(somearray,function(){...}); it is virtually the same as if you called somearray.map(function(){...});. Array.map is just a utility method Javascript in Firefox only (another reason why not to use it) has to make life easier. The Array.map function is not cross-browser.

Edit: The reason that they had to use Array.prototype.map.call(links,...); instead of just links.map(...);, is that querySelectorAll does not return a normal array, it returns a NodeList that does not have a map method.