Summary  
The do-while loop executes a code block at least once before evaluating its condition and continues iterating until that condition is false.

General domain of usage  
Prompting and validating user input

Let's consider the **do-while** loop. This loop is similar to the **while** loop but has a key distinction.

# Syntax
The **do-while** loop begins with the `do` keyword, encloses the code block within curly braces `{}`, and concludes with the `while` keyword followed by the condition in parentheses `()` without the need for an additional code block:
```js
do {
  // code block
} while (condition);
```
Here's an example:

let a = 0;

do {
  console.log(a);
  a++;
} while (a <= 3 && a >= 1);

At the outset, the variable `a` was initialized to `0`, and the condition `a >= 1` was evaluated after the `a++` operation.

The code block within the `do` is guaranteed to be executed at least once:

// `while` loop
while (false) {
  console.log("while"); // Not executed
}

// `do-while` loop
do {
  console.log("do-while"); // Executed 1 time
} while (false);

The **do-while loop** is particularly useful when you need to prompt the user for input at least once and continue until the user enters valid data or meets a specific condition.

How many times will the following code print `"Invalid PIN"` to the console?

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Using the do while Loop for Iteration

Syntax