I have arr = [1,2,3] and ids = [1,2,3,4,5,6]. I want to find if any of the arr item exist in the ids. If yes the invalid is true.
Which of the below code is better? or they are the same thing?
const invalid = !arr.every((id) => ~ids.indexOf(id));
const invalid = arr.some((id) => ids.includes(id));
The two statements have a very different semantics.
The callbacks are the same, ie ids.includes(id) === true is equivalent to ~ids.indexOf(id) != 0. But arr.some() and !arr.every() have a different semantics:
some() returns true if at least one element fits the condidition!every() returns true if at least one element doesn't fit the conditionSo actually your first snippet is not checking, if there is at least one element in arr that is also contained in ids, but if there is at least one element in arr that is not contained in ids
So the correct version of first snippet would be
const invalid = !arr.every((id) => !(~ids.indexOf(id)));
Ie, checkig if not every element of arr is not contained in ids. From a computational standpoint, they are more or less the same:
indexOf and includes return on the first element element they findsome stops when the callback returns true for the first timeevery stops when the callback returns false for the first time~ and !But if you compare this to your second snippet, it seems pretty obvious, that it is far more complex to read and understand and therefore far more complex to maintain.
const
arr = [1,2,3],
ids = [1,2,3,4,5,6]
const
i1 = !arr.every((id) => ~ids.indexOf(id)),
i2 = arr.some((id) => ids.includes(id)),
i3 = !arr.every((id) => !(~ids.indexOf(id)));
console.log(i1, i2, i3)