Does it mutate 😱

Array.prototype.every

No mutation

Description

The every() method tests whether all elements in the array pass the test implemented by the provided function.

Array.prototype.every ( callbackfn [ , thisArg ] )

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/every

Example

function isBelowThreshold(currentValue) {
  return currentValue < 40;
}

var array1 = [1, 30, 39, 29, 10, 13];

console.log(array1.every(isBelowThreshold));
// expected output: true