Check if all values in array are true, then return a true boolean statement (javascript)

Question

I have an array of booleans, which begins as false, because at least one of the values is false: var validation = [false, true, true] In certain moment, it'll have all the options(index) as "true", like: validation = [true, true, true] How can I set this array as "true" when all the options are true?

Sorry for the silly question.

You could also use "some" for example: var arr = [true, true, true, true, true, true ]; var allTrue = !arr.some(x => x === false); console.log(allTrue); — darmis, Dec 22 '18 at 17:49
@darmis moreover `some` will be faster as it will stop as soon as it finds `false` - no need to check every item to see if they all `true` — godblessstrawberry, Jul 08 '21 at 09:50

Mohammad Usman · Accepted Answer · 2018-12-22T17:10:42.947

177

You can use .every() method:

let arr1 = [false, true, true],
    arr2 = [true, true, true];

let checker = arr => arr.every(v => v === true);

console.log(checker(arr1));
console.log(checker(arr2));

As mentioned by @Pointy, you can simply pass Boolean as callback to every():

let arr1 = [false, true, true],
    arr2 = [true, true, true];

let checker = arr => arr.every(Boolean);

console.log(checker(arr1));
console.log(checker(arr2));

edited Dec 22 '18 at 17:10

answered Dec 22 '18 at 17:06

Mohammad Usman

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Or simply `let result = arr1.every(Boolean);` - the Boolean constructor will return `true` or `false`. – Pointy Dec 22 '18 at 17:08
`Boolean` means that it cast each array member into Boolean value right? – buncis May 13 '23 at 10:51
@buncis in short yes. `Boolean` is a built in function available that will cast its argument to corresponding boolean value when used without `new` operator. – Mohammad Usman May 15 '23 at 04:30

score 32 · Answer 2 · answered Dec 22 '18 at 17:12

32

You can use this to check if every values in array is true,

validation.every(Boolean)

answered Dec 22 '18 at 17:12

Sandeepa

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This would fail if it includes strings `["FALSE"].every(Boolean)` would return true – TOLULOPE ADETULA Aug 09 '21 at 16:24
10

@TOLULOPEADETULA That is expected. "FALSE" is a truthy value in JS. You cannot evaluate string values to false based on their content – Abhishek Agarwal Sep 06 '21 at 12:32
`Boolean` means that it cast each array member into Boolean value right? – buncis May 13 '23 at 10:51

score 11 · Answer 3 · answered Dec 22 '18 at 17:08

11

You can check if array have "false" value using "includes" method, for example:

if (validation.includes(value)) {
    // ... your code
}

answered Dec 22 '18 at 17:08

Anlis

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no this doesn't do justice for all values, it only check if one of the array value includes your value! – Danish Oct 24 '22 at 17:55
1

@Danish if (!validation.includes(false)) { } for example. Although .every() is much better!! – Jamie G Dec 14 '22 at 22:11
`includes` is definitely better because I believe `every` is ES6 and above, or just a very new feature. I don't use `includes` as often as `indexOf`, so I'll use that :) – RixTheTyrunt Jun 21 '23 at 14:16

Check if all values in array are true, then return a true boolean statement (javascript)

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