Question

In PHP there is func_num_args and func_get_args, is there something similar for JavaScript?

Answer 1

For modern Javascript or Typescript:

class Foo {
    reallyCoolMethodISwear(...args) { return args.length; }
}

function reallyCoolFunction(i, ...args) { return args[i]; }

const allHailTheLambda = (...args) => {
    return args.constructor == Array;
};

const x = new Foo().reallyCoolMethodISwear(0, 1, 2, 3, 4);
const y = reallyCoolFunction(3, 0, 1, 2, 3, 4, 5, 6);
const z = allHailTheLambda(43110, "world");

console.log(x, y, z); // 5 3 true

For ancient Javascript:

Use arguments. You can access it like an array. Use arguments.length for the number of arguments.