Rename Tail to Shift might be better

[wjw99830]

The behavior of Tail is similar to Array.prototype.shift.

[almamunhossen]

You're close, but actually the opposite is true in most languages!

In JavaScript:

• Array.prototype.shift() → removes and returns the first element (from the head)
• There is no built-in Array.prototype.tail() method

If you see code that defines a .tail() method or function, it usually does the opposite of shift():

// Common functional-programming style "tail"
function tail(arr) {
  return arr.slice(1);  // returns everything EXCEPT the first element
}

// or as a prototype method
Array.prototype.tail = function() {
  return this.slice(1);
};

const arr = [1, 2, 3, 4];
console.log(arr.shift()); // → 1    (mutates arr → [2,3,4])
console.log(tail(arr));   // → [2,3,4,3,4] wait no, better example:
console.log(tail([1,2,3,4])); // → [2,3,4]  (does NOT mutate original)

Summary of the difference:

Operation	Removes/Returns	Mutates original?	Common in FP?
arr.shift()	First element (head)	Yes	No
tail(arr)	All but first (tail)	Usually no	Yes

In other languages/contexts:

• Haskell: tail [1,2,3,4] → [2,3,4] (everything except head)
• Lisp/Scheme: (cdr '(1 2 3 4)) → (2 3 4)
• Python: often lst[1:] or itertools.islice

So the statement “The behavior of Tail is similar to Array.prototype.shift” is incorrect.

Correct statement:
Tail returns the list without the first element (similar to slice(1) or [1:]),
while shift() removes and returns the first element itself and mutates the array.

They are essentially complementary operations, not similar ones.