Is anonymous function expression?

Question

Is an anonymous function expression? if it is, why can not we use it wherever JavaScript expects an expression?

Example :

const result = String(function () {
    return 2;
});

what variable returns :

'function () {\r\n    return 2;\r\n}'

but I expected to get 2 in string format because if anonymous function is expression it must return 2 as the argument for the String function

I tried to use an anonymous function where js expects an expression but i did not get the result what i expected

Answer 1

You forgot to invoke the function. A function definition by itself is just that, a definition. If it's never invoked, it won't return the value.

(And interpreting a function definition as a string results in the text of the function, which is the result you're observing.)

const result = String(function () {
    return 2;
}()); // Note the additional () here
console.log(result);