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JavaScript Recipes: Get Index in for...of Loop

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A for-of loop, introduced in ES6, is a great way to iterate over an array:

for (const v of ['a', 'b', 'c']) {
  console.log(v)
}

How can you get the index of an iteration?

The loop does not offer any syntax to do this, but you can combine the destructuring syntax introduced in ES6 with calling the entries() method on the array:

for (const [i, v] of ['a', 'b', 'c'].entries()) {
  console.log(i, v)
}

This outputs:

0 'a'
1 'b'
2 'c'

Lessons in this unit:

0: Introduction
1: Generate Random Numbers in a Range
2: ▶︎ Get Index in for...of Loop
3: Unlimited Function Parameters
4: Return Result from Async Function
5: Encode and Decode URLs
6: Destructuring Tips
7: Number Formatting
8: Regex Recipes
9: Dynamic function name in JS