JavaScript: Array.prototype.some

arrayX.some(f)

Return true if the function f return true for at least one element.

As soon as f return true, exit the iteration and return true.

If array is empty, return false.

arrayX can be Array-Like Object.

The function f is passed 3 args:

1. currentElement
2. currentIndex
3. arrayX.

const ff = ((x) => (x === 3));

console.log([1, 2, 3, 4, 5, 6].some(ff) === true);

arrayX.some(f, thisArg)

Use thisArg for this Binding of f

Use “some” as Loop with Break

some is useful functional programing style of a loop that exit when a condition is met. (similar to forEach with break.)

Here is example. Apply f to each element in order. Exit the loop when f returns true.

const ff = ((x) => {
  console.log(x);
  return x === 3;
});

[1, 2, 3, 4, 5, 6].some(ff);

/*
prints
1
2
3
*/

method 「some」 on Empty Array

some on empty array returns false.

console.log([].some((x) => true) === false);