How do you access the index of an element in an array during iteration?
TL;DR
To access the index of an element in an array during iteration, you can use methods like forEach, map, for...of with entries, or a traditional for loop. For example, using forEach:
const array = ['a', 'b', 'c'];array.forEach((element, index) => {console.log(index, element);});
Using forEach
The forEach method executes a provided function once for each array element. The callback function takes three arguments: the current element, the index of the current element, and the array itself.
const array = ['a', 'b', 'c'];array.forEach((element, index) => {console.log(index, element);});
Using map
The map method creates a new array populated with the results of calling a provided function on every element in the calling array. The callback function also takes three arguments: the current element, the index of the current element, and the array itself.
const array = ['a', 'b', 'c'];array.map((element, index) => {console.log(index, element);});
Using for...of with entries
The for...of loop can be combined with the entries method to access both the index and the element.
const array = ['a', 'b', 'c'];for (const [index, element] of array.entries()) {console.log(index, element);}
Using a traditional for loop
A traditional for loop gives you direct access to the index.
const array = ['a', 'b', 'c'];for (let index = 0; index < array.length; index++) {console.log(index, array[index]);}