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

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
– darmis, Commented Dec 22, 2018 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
– godblessstrawberry, Commented Jul 8, 2021 at 9:50

Mohammad Usman · Accepted Answer · 2018-12-22 17:10:42Z

202

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, 2018 at 17:10

answered Dec 22, 2018 at 17:06

Mohammad Usman

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3 Comments

Pointy Over a year ago

Or simply let result = arr1.every(Boolean); - the Boolean constructor will return true or false.

buncis Over a year ago

Boolean means that it cast each array member into Boolean value right?

Mohammad Usman Over a year ago

@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.

Sandeepa · Accepted Answer · 2018-12-22 17:12:03Z

41

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

validation.every(Boolean)

answered Dec 22, 2018 at 17:12

Sandeepa

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3 Comments

TOLULOPE ADETULA Over a year ago

This would fail if it includes strings ["FALSE"].every(Boolean) would return true

Abhishek Agarwal Over a year ago

@TOLULOPEADETULA That is expected. "FALSE" is a truthy value in JS. You cannot evaluate string values to false based on their content

buncis Over a year ago

Boolean means that it cast each array member into Boolean value right?

Anlis · Accepted Answer · 2018-12-22 17:08:00Z

13

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

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

answered Dec 22, 2018 at 17:08

Anlis

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3 Comments

Danish Over a year ago

no this doesn't do justice for all values, it only check if one of the array value includes your value!

Jamie G Over a year ago

@Danish if (!validation.includes(false)) { } for example. Although .every() is much better!!

John GradientOS Over a year ago

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 :)

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