Is \'clear\' a Reserved Keyword in JavaScript, and Why Might a `clear()` Function Fail?

Is "clear" a Reserved Word in Javascript?

A user encountered an issue where invoking the clear() function had no effect, while other functions in the same codebase worked as expected. After investigating, they discovered that renaming the clear() function resolved the issue. This led to the question of whether the word "clear" is a reserved word in Javascript.

Reserved Word Check

Upon checking the Mozilla Developer Network (MDN) documentation, "clear" is not listed among the reserved words in Javascript. This means that it is available for use as a function name or other identifier.

Scope Chain Resolution

The issue in the code was due to a quirk in the scope chain for event handlers attached as HTML attributes. When using inline event handlers, the Document object is in the scope chain earlier than the Window object.

Since the clear() function was defined in the global scope as a property of the window object, it was not found in the scope chain because document.clear had precedence. This issue can arise when form elements are present within a form, as their corresponding form elements may also be present in the scope chain.

Debugging Techniques

To resolve this type of issue, the following debugging techniques can be employed:

• Use console logging to check the scope chain and identify if a function or variable exists in it.
• Use the debugger keyword to pause execution and examine the current scope chain.
• Consider using an external debugging tool, such as the Chrome DevTools or Firefox Debugger.

Prevention Strategies

To avoid such issues, it is recommended to:

• Avoid using inline event handlers and attach them using alternative methods, such as event listeners or using a framework.
• Avoid polluting the global namespace by encapsulating code within a custom object or using namespaces.

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