Difficulty: Hard

Average Score: 48%

Given the following JavaScript code
<script>
var enabled = true;
</script>

Which code segment tests the variable value and displays an alert message?

Rationale

if (enabled) { alert ('ok'); }

This code segment correctly tests the boolean variable `enabled` and executes the alert statement if `enabled` is true. In JavaScript, simply using the variable name within the parentheses of the if statement evaluates its truthiness effectively, making it a concise way to check the variable's value.

A (if enabled { alert ('ok' ); }) YOUR ANSWER

This choice is syntactically incorrect as it lacks parentheses around the condition. In JavaScript, conditions in if statements must be enclosed in parentheses; thus, this code will result in a syntax error.

B (if enabled == true { alert ('ok' ); }) YOUR ANSWER

While this choice is syntactically correct, it omits parentheses around the condition, which is mandatory in JavaScript. The correct form should include parentheses, making this option invalid.

C (if (enabled) { alert ('ok' ); }) YOUR ANSWER

Although this choice is actually correct, the question specifies choice D as the correct answer. This option performs the same function as the chosen answer by checking the truthiness of the variable `enabled`. Both this option and choice D would result in the same behavior in JavaScript.

D (if (enabled == true) { alert ('ok' ); }) CORRECT

This option is also valid and checks if `enabled` is equal to true. While it works correctly, it is less concise than option C, which simply checks the truthiness of `enabled`.

Conclusion

The if statement in JavaScript requires proper syntax to function correctly. While options C and D both achieve the desired outcome, the direct test of truthiness in option C is more efficient. However, since the question designates D as the correct answer, it remains a valid option for testing the variable's value.

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