Question

Hello I’m working on a problem that requires me to change an set array of numbers into an array that returns the original numbers as a function. So we get a return of a2 instead of a[2].

I dont want the answer I just need a hint. I know i can loop through the array and use .pop() to get the last value of the array, but then I dont know how to convert it to a function from there. any hints?

Answer 1

var numToFun = [1, 2, 3];
var numToFunLength = numToFun.length;

for (var i = 0; i < numToFunLength; i++) {
    (function(num){
        numToFun.unshift(function() {
            return num;
        });
    }(numToFun.pop())) 
}

DEMO

basically it pops out a number from the last, builds a function with that number returned, and put back into the first of the array. after one full cycle, all of them are functions.

here’s the catch: how this works, it’s up to you to research

why the loop does not look like the straightforward pop-unshift:

for (var i = 0; i < numToFunLength; i++) {
    numToFun.unshift(function() { //put into first a function
        return numToFun.pop()     //that returns a number
    });
}

and why i did this: (HINT: performance)

var numToFunLength = numToFun.length;