Q
Which of the following is a recommended practice for optimizing JavaScript performance?

Answer & Solution

Answer: Option A
Solution:
Minifying and concatenating scripts reduces file size and HTTP requests, optimizing JavaScript performance. Including all scripts in the <head> can lead to longer page load times, whereas synchronous loading can block rendering and affect performance negatively.
Related Questions on Average

When JavaScript is placed in the <head> section of an HTML document, it can:

A). Execute before page rendering.

B). Execute after page rendering.

C). Block rendering until execution.

D). None of the above.

How can JavaScript be loaded asynchronously in the <body> section without blocking page rendering?

A). Using the defer attribute.

B). Using the async attribute.

C). Including scripts in the <head>.

D). Not possible in the <body>.

Placing JavaScript in the <head> section can impact page load times because:

A). It blocks rendering until executed.

B). It loads scripts asynchronously.

C). It reduces HTTP requests.

D). It has no impact on loading.

What is the purpose of using the async attribute with an external JavaScript file?

A). To load the script asynchronously.

B). To defer script execution.

C). To block rendering until script loads.

D). To ensure script execution order.

Placing JavaScript at the end of the <body> section is beneficial for:

A). Improving page load speed.

B). Blocking page rendering.

C). Increasing script complexity.

D). Hiding script functionalities.

Which attribute should be used for loading external JavaScript files without blocking rendering in the <head> or <body> sections?

A). async

B). defer

C). sync

D). load

Variables declared in the <head> section of an HTML document are accessible:

A). Globally throughout the document.

B). Only within the <head> section.

C). Only after the page has fully loaded.

D). Nowhere in the document.

When using an external JavaScript file in the <head> section with the defer attribute, when does it get executed?

A). After the HTML content is fully parsed.

B). Before the HTML content is parsed.

C). As soon as it starts loading.

D). After all other scripts in the <head>.

Variables declared in the <body> section of an HTML document have what scope by default?

A). Local to the script or function.

B). Global throughout the document.

C). Limited to the <body> section.

D). Not accessible in JavaScript.

What is the advantage of placing JavaScript at the end of the <body> section for non-critical scripts?

A). Faster initial page rendering.

B). Slower page load overall.

C). Better script execution order.

D). Increased script complexity.

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