TIL: JavaScript Arguments Object

JavaScript has a built-in arguments object in every function that lets you access the arguments passed to a function, even if the function doesn’t have any listed parameters! (What. What.)

function foo() {
  // This is fine, apparently?
  console.log(arguments[0]);
  // Expected output: 1
}

foo(1);

Interestingly, it’s an “array-like” object, so you can use a for-of loop on it, but it isn’t an array, so you can’t use e.g. forEach; to get an array, you have to use Array.from() or the spread operator.

References

• “The arguments object”