What are the purposes of comments in JavaScript code?
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Comments can make the code easier to understand.
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Comments can help hide the code from browsers that cannot interpret JavaScript.
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Comments can help display a warning to users of old browsers that do not support JavaScript.
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All of above.
All three purposes are valid: comments improve code readability for developers, can hide scripts from browsers that don't support JavaScript (using HTML-style comments), and can display warnings to users with outdated browsers. Therefore 'All of above' is correct.
'All of above' is correct because JavaScript comments (// and /* */) serve multiple purposes simultaneously: they make code more readable/maintainable for developers, they can be used cleverly (historically, wrapping script content in HTML comments) to hide script code from very old browsers that don't parse tags, and they can display fallback text/warnings to users on browsers without JavaScript support (often via <noscript> combined with commenting techniques). Since all three listed purposes are legitimate uses, the comprehensive answer is correct.