Javascript - matching first value from array search with value from other array

Question

So let's say we have two arrays

const arr1 = [1, 2, 3, 4, 5];

const arr2 = [6, 7, 8, 9, 10, 4, 5,];

I want to return just the first matching value without doing two for loops. So not by taking first value from arr1 look for it in arr2 then second value ect.

I this case I would need to return 4.

Working in React/Redux enviroment without jQuery possible.

I working with quite a large number of data so the for loops take long time to execute. Last one I did took around 20 seconds — Hayk Shakhbazyan
– Hayk Shakhbazyan, Commented Oct 12, 2017 at 13:47

BenW · Accepted Answer · 2017-10-12 13:41:53Z

3

const arr1 = [1, 2, 3, 4, 5];

const arr2 = [6, 7, 8, 9, 10, 4, 5,];

arr1.find((x) => arr2.indexOf(x) >=0);

That'll grab the first match

answered Oct 12, 2017 at 13:41

BenW

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2 Comments

pete Over a year ago

Shouldn't it return indexOf(x) > -1?

yqlim Over a year ago

@pete 0 >= 0 is the same as 0 > -1

Nenad Vracar · Accepted Answer · 2017-10-12 13:42:37Z

0

You can use find() with includes() method.

const arr1 = [1, 2, 3, 4, 5];
const arr2 = [6, 7, 8, 9, 10, 4, 5,];

var r = arr1.find(e => arr2.includes(e));
console.log(r)

answered Oct 12, 2017 at 13:42

Nenad Vracar

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Comments

RomanPerekhrest · Accepted Answer · 2017-10-12 13:46:05Z

0

Ecmascript5 solution (with Array.some() function):

var arr1 = [1, 2, 3, 4, 5],
    arr2 = [6, 7, 8, 9, 10, 4, 5,],
    result;
	
arr2.some(function(n){ return arr1.indexOf(n) !== -1 && (result = n) })

console.log(result);

answered Oct 12, 2017 at 13:46

RomanPerekhrest

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Comments

Nina Scholz · Accepted Answer · 2017-10-12 13:51:10Z

0

You could use the power of Set.

const
    arr1 = [1, 2, 3, 4, 5],
    arr2 = [6, 7, 8, 9, 10, 4, 5],
    result = arr2.find((s => a => s.has(a))(new Set(arr1)));

console.log(result);

answered Oct 12, 2017 at 13:51

Nina Scholz

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