Sometimes, we want to find index of all occurrences of element in array with JavaScript.

In this article, we’ll look at how to find index of all occurrences of element in array with JavaScript.

How to find index of all occurrences of element in array with JavaScript?

To find index of all occurrences of element in array with JavaScript, we use the array map method.

For instance, we write

const indices = array.map((e, i) => (e === value ? i : "")).filter(String);

to call map with a callback that checks if array entry e is equal to value.

If it is, we return i.

Otherwise, we return an empty string.

And we call filter with String to filter out all the empty strings since they’re falsy.

Conclusion

To find index of all occurrences of element in array with JavaScript, we use the array map method.