Question

I have been writing javascript for one or two months , I never used Function keyword , like Function.method(); when I define function , I simply define it as :

function fooBar () {};

Can you give me an example when using Function is more convenient ?

Answer 1

You shouldn’t use the Function constructor so often, it basically uses code evaluation to build a function.

It requires string arguments, being the last argument the function body, and the previous ones will be the arguments of the new function itself, for example:

var add = new Function("a", "b", "return a + b;");
add(5,5) == 10;

When you should use it?

As I said not so often, I personally try to avoid them since they use code evaluation.

A thing to note is that no closures are created when functions are built in this way, which can be a good thing for some performance circumstances, for example to shorten the process of identifier resolution, but you should use them with care…