How to check whether multiple values exist within an Javascript array

Question

So, I\'m using Jquery and have two arrays both with multiple values and I want to check whether all the values in the first array exist in the second.

Answer 1

Using array functions: [].filter and [].includes

Something like this:

[34, 78, 89].filter((v) => {
    return [78, 67, 34, 99, 56, 89].includes(v);
});

This will return an array of the matches items

Then we can compare it with needles array

As a function it will be:

const contains = (haystack, needles) => {
    return haystack.filter((v) => {
        return needles.includes(v);
    }).length === needles.length;
}

Answer 2

A one-liner to test that all of the elements in arr1 exist in arr2...

With es6:

var containsAll = arr1.every(i => arr2.includes(i));

Without es6:

var containsAll = arr1.every(function (i) { return arr2.includes(i); });

Answer 3

If you need a little bit more visibility on which items are in the array you can use this one :

var tools = {
        elem : {},
        arrayContains : function(needles, arrhaystack) {
           if (this.typeOf(needles) === 'array') {
                needle.reduce(function(result,item,$i,array){ // You can use any other way right there.
                    var present = (arrhaystack.indexOf(item) > -1);
                    Object.defineProperty(tools.elem, item, {
                        value : present,
                        writable : true
                    });
                },{})
                return this.elem;
            }
        },        
        typeOf : function(obj) {
            return {}.toString.call(obj).split(' ')[1].slice(0, -1).toLowerCase();
        }
    }

Use it with simply var check = tools.arrayContains([10,'foo'], [1,'foo','bar'])

Then you get the result like

10 : false
foo : true

Then if you need to get only one result if one of them is true you can :

arr = Object.values(check);
(arr.indexOf('true')) ? instru1 : instru2 ;

I don't think that's the better way but it's working & easily adaptable. Considering this example I advise you to make an Object.create(tools) before use it in your way.

Answer 4

You can use this simple function (renamed variables as per above answer for easy reading):

function contains(haystack, needles) {

    return needles.map(function (needle) { 
        return haystack.indexOf(needle);
    }).indexOf(-1) == -1;
}

Answer 5

Just for the fun of it, i've implemented something with Array.prototype.reduce() :

let areKeysPresent = function (sourceArray, referenceArray) {
    return sourceArray.reduce((acc, current) => acc & referenceArray.includes(current), true)
}

Answer 6

You could take a Set and check all items agains it.

const
    containsAll = (needles, haystack) =>
        needles.every(Set.prototype.has, new Set(haystack));

console.log(containsAll([105, 112, 103], [106, 105, 103, 112]));