confused-about-call.js

// I am confused about how you can use `call` without supplying an object for `this`
// The docs don't indicate that you can: 
// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function/call

var funny = function (a) { return (a + 3); }
funny(3);           // 6
funny.call({},3);   // 6
funny.call(3);      // NaN  // (as expected)

var xs = [1,2,3]
var pop = Array.prototype.pop;
pop.call(xs);       // 3          // Why does this work ...
pop.call({}, xs);   // undefined  // ... but this does not?

Ah OK so I was misinterpreting pop as a "pull the last thing off the given array" when it is really "pull that last thing off the array you are attached to". Seems obvious in retrospect - thanks @chilts!