Let's break down what's being tested and compared in this benchmark.

Benchmark Description

The benchmark is called "class vs id test 3". It compares two ways of selecting an HTML element using JavaScript:

1. document.getElementById("id1");
2. document.querySelector(".cl2");

Test Cases

There are two individual test cases:

1. "id": This test case uses the method document.getElementById("id1"); to select an HTML element.
   • Library: None (built-in JavaScript API)
   • Special JS feature or syntax: None
   • Purpose: This method is used to retrieve an HTML element by its ID attribute.
2. "class": This test case uses the method document.querySelector(".cl2"); to select an HTML element.
   • Library: None (built-in JavaScript API)
   • Special JS feature or syntax: querySelector() and CSS selector syntax
   • Purpose: This method is used to retrieve an HTML element by its class attribute.

Comparison

The benchmark measures the execution time per second for each test case. The results show that:

• The "id" test case has a higher execution rate (8,330,404 executions per second) than the "class" test case (5,009,300 executions per second).
• This suggests that selecting an element by ID is faster than selecting it by class.

Pros and Cons

Here's a brief summary of each approach:

1. document.getElementById()
   • Pros: Faster execution time, better performance for large documents.
   • Cons: Only retrieves one element with the specified ID.
2. document.querySelector()
   • Pros: Can retrieve multiple elements that match the CSS selector, flexible and powerful syntax.
   • Cons: Slower execution time compared to getElementById(), can be less efficient for large documents.

Other Alternatives

If you need to select an HTML element by its class attribute, you can use other methods:

1. document.getElementsByClassName(): Returns a list of elements with the specified class name.
2. querySelectorAll(): Similar to querySelector(), but returns a NodeList of matching elements.

Keep in mind that these alternatives might have different performance characteristics and are not directly compared in this benchmark.