Boolean algebra in javascript

Question

Is there any way to use boolean algebra in JS?

Eg I would like to loop through an array containing true & false, and simplify it down to either only true, or false.

Doing it with boolean algebra seems like an elegant way to do it...

would like to do a comparison that lets me simply add the previous value to the current iteration of a loop

[true, true, true, true] // return true

[false, true, true, true] // return false

Do you mean 'and-ing' them all together?

n8wrl
– n8wrl

2011-07-14 18:04:50 +00:00
Commented Jul 14, 2011 at 18:04 — n8wrl
– n8wrl, Commented Jul 14, 2011 at 18:04

Lourens · Accepted Answer · 2011-07-14 18:09:04Z

21

I think a simple solution would be

return array.indexOf(false) == -1

answered Jul 14, 2011 at 18:09

Lourens

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2 Comments

Adam Over a year ago

This won't work in ie7 or less, unless you define the indexOf function manually

Lomefin Over a year ago

This looks faster, but later on it could become a little harder to understand what is doing here.

Lomefin · Accepted Answer · 2022-12-14 15:30:42Z

17

Try Array.reduce:

[false,true,true,true].reduce((a,b) => a && b)  // false

[true,true,true,true].reduce((a,b) => a && b) // true

edited Dec 14, 2022 at 15:30

Lomefin

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answered Jul 14, 2011 at 18:12

digitalbath

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Comments

David Wolever · Accepted Answer · 2011-07-14 18:05:34Z

7

You mean like:

function all(array) {
    for (var i = 0; i < array.length; i += 1)
        if (!array[i])
            return false;
    return true;
}

Or is there something more complex you're looking for?

answered Jul 14, 2011 at 18:05

David Wolever

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1 Comment

nnnnnn Over a year ago

+1 because it's simple, could easily be converted to handle a requirement of logical OR instead of AND, and it's essentially the same as the accepted answer that uses .indexOf() except it will work in all browsers.

Adam · Accepted Answer · 2011-07-14 18:27:29Z

2

function boolAlg(bools) {    
    var result = true;

    for (var i = 0, len = bools.length; i < len; i++) {
        result = result && bools[i]

    }

    return result;
}

Or you could use this form, which is faster:

function boolAlg(bools) {    
    return !bools[0] ? false :
        !bools.length ? true : boolAlg(bools.slice(1));
}

edited Jul 14, 2011 at 18:27

answered Jul 14, 2011 at 18:11

Adam

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Comments

uadnal · Accepted Answer · 2011-07-14 18:06:44Z

1

for(var i=0; i < array.length;++i) {
   if(array[i] == false)
      return false;
}
return true;

answered Jul 14, 2011 at 18:06

uadnal

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Comments

k.tten · Accepted Answer · 2022-12-14 03:29:00Z

1

ES6 Array.prototype.every:

console.log([true, true, true, true].every(Boolean));
console.log([false, true, true, true].every(Boolean));

answered Dec 14, 2022 at 3:29

k.tten

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