javascript .filter() true booleans

Question

function bouncer(arr) {   // Don't show a false ID to this bouncer.     function a(b) {       if(b !== false) {         return b;       }     }      arr = arr.filter(a);     return arr; }  bouncer([7, 'ate', '', false, 9]); 

I have to return true boolean statements only, and when I run this code, it works. However, I am quite confused because my "if statement" will work whether it's b !== true or b !== false. Could someone please explain the reason why this works both ways?

Answer 1

Apparently .filter() was introduced in ES5.

This definitely helped me wrap my mind around what's going on here. Hope it helps!

Essentially, writing:

arr.filter(Boolean) 

is the same as writing:

arr.filter( function(x) { return Boolean(x); });  

since Boolean() is also a function that returns truthy when true and falsy when false!

Example:

var a = [1, 2, "b", 0, {}, "", NaN, 3, undefined, null, 5];  var b = a.filter(Boolean);  // [1, 2, "b", {}, 3, 5];  

Source: here.

Answer 2

I was solving a similar problem and came up with this:

function bouncer(arr) {   return arr.filter(Boolean); } console.log(bouncer([7, 'ate', '', false, 9]));