Loops: The `do-while` loop

The do..while loop might be less powerful than for but it’s also simpler to setup.

With this loop we do something, which we define in a block, and then we decide if we want to do it again.

We have to define an index variable outside of it before we can use it, so it’s more verbose than for.

Here’s the example we saw in the for lesson, transformed for do..while:

const list = ['a', 'b', 'c']

let i = 0

do {
  i = i + 1
} while (i < list.length)

Notice that we also have to increment i manually. If you forget to do so, you will create what’s called an infinite loop.

You can interrupt a while loop using break:

do {
  if (something) break
} while (true)

and you can jump to the next iteration using continue:

do {
  if (something) continue

  //do something else
} while (true)

Lessons in this unit:

0: Introduction
1: The `for` loop
2: ▶︎ The `do-while` loop
3: The `while` loop
4: The `for-of` loop
5: The `for-in` loop
6: Other kinds of loops
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