Htykuut

All the blogs and videos I peruse about the JS runtime talk about the stack, heap, and queue. One thing none of those examples have explained are what happens to function declarations when they are passed by the runtime?

No source I've seen talks about function declarations being stored in memory or having any sort of flag to reference to go back to that point, after the function is initially invoked.

For example, consider the following blog: https://blog.sessionstack.com/how-does-javascript-actually-work-part-1-b0bacc073cf

This particular blog post explains the call stack, but does not explain what happens to the function declaration multiply(x, y). Is it in any way stored or referenced for a future invocation?

function multiply(x, y) {

    return x * y;

}

function printSquare(x) {

    var s = multiply(x, x);

    console.log(s);

}

printSquare(5);

The code is evaluated in two stages: at first it gets parsed and then evaluated. During parsing, so-called EnvironmentRecords are created. The spec says:

Each declarative Environment Record is associated with an ECMAScript program scope containing variable, constant,
let, class, module, import, and/or function declarations. A declarative Environment Record binds the set of identifiers
defined by the declarations contained within its scope.

During evaluation phases, identifiers are looked up in the current environment record.

They are added to the global window object, just like global variables.

function multiply(x, y) {

    return x * y;

}

function printSquare(x) {

    var s = multiply(x, x);

    console.log(s);

}

printSquare(5);



console.log(window.multiply(2,2));