JavaScript do...while Loop

The do...while loop in JavaScript is used when you want to execute a block of code at least once, and then repeat it as long as a condition is true. Unlike a regular while loop, the do block runs before checking the condition.

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Syntax

• The code block runs once initially.
• The condition is evaluated after the first iteration.

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Example 1: Basic do...while Loop

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Example 2: Run At Least Once

Even though the condition was initially false, the block still ran once.

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Example 3: With continue and break

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When to Use do...while

• When you want to guarantee at least one execution.
• For user prompts, input validation, or retry mechanisms.
• When loop logic and validation are tightly coupled.

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Key Takeaways

• do...while always runs the loop at least once.
• The condition is checked after running the code block.
• Best for logic that must execute once, regardless of condition.
• Use break to exit early and continue to skip iterations.
• Make sure the condition eventually becomes false to avoid infinite loops.