JavaScript Why return function in a function?

Question

var favoriteColor = \"blue\";
function colorGenerator(color) {
    return function () { return color; };
}
var getColor = colorGenerator(favoriteColor);

Answer 1

It's called making a closure. Basically for each call of that colorGenerator function the vars local to it will stay around and be represented in the call of the function it returns.

See this:

function colorGenerator(color) {
    return function () { return color; };
}

// remember these are functions to be called, not the actual color names
var getRed = colorGenerator('red');
var getBlue = colorGenerator('blue');

// now each time we call the returned function of
// each, it will say the color we want
alert( getRed() + " and " + getBlue() ); // -> "red and blue"

I don't know the context of this snippet of code, so why you'd basically need a factory for making functions that return a certain color name, I don't know. But that's essentially what it'll do.

For explaining why that would be useful in a certain context we'd probably have to know the context...