Question

163

forEach loop through two arrays at the same time in javascript

rated 0 times [ 169] [ 6] / answers: 1 / hits: 85224 / 5 Years ago, thu, september 12, 2019, 12:00:00

I want to build a for loop that iterates through two variables at the same time. n is an array and j goes from 0 to 16.

var n = [1,2,3,5,7,8,9,11,12,13,14,16,17,18,20,21,22];

var m = [0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16];



m.forEach(k => {

    n.forEach(i => {

        console.log(i, k)

    });

};

The final result should output:

1,0

2,1

3,2

5,3

(...)

Unfortunately this loop doesn't do that for some reason as it repeats every number 17 times.

What am I missing here?

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jaylynbrynnk

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3 Years ago

answered 5 Years ago ravenl · Accepted Answer

Use the second parameter forEach accepts instead, which will be the current index you're iterating over:

n = [1,2,3,5,7,8,9,11,12,13,14,16,17,18,20,21,22];



n.forEach((element, index) => {

  console.log(element, index);

});

If you have two separate arrays to begin with, in each iteration, access the [index] property of the other array:

var n = [1, 2, 3, 5, 7, 8, 9, 11, 12, 13, 14, 16, 17, 18, 20, 21, 22];

var m = [0, 1, 2, 3, 4, 5, 6, 7,  8,  9,  10, 11, 12, 13, 14, 15, 16];



n.forEach((num1, index) => {

  const num2 = m[index];

  console.log(num1, num2);

});