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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?
941
To use forEach to loop through two arrays at the same time in JavaScript, we can use the index parameter of the forEach callback to get the element with the same index from the 2nd array. const n = [1, 2, 3, 5, 7, 8, 9, 11, 12, 13]; const m = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]; n.
Note: forEach expects a synchronous function. forEach does not wait for promises. Make sure you are aware of the implications while using promises (or async functions) as forEach callback.
forEach is almost the same as for or for..of , only slower. There's not much performance difference between the two loops, and you can use whatever better fit's the algorithm. Unlike in AssemblyScript, micro-optimizations of the for loop don't make sense for arrays in JavaScript.
JavaScript is, for the most part, single-threaded. There are no parallel operations like that in the language.
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); });If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
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