Benchmark: .endsWith vs .charAt for single char

HTML Preparation code:

<div></div>

Script Preparation code:

var data = window.data = [];
const possible = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
var TOTAL_STRINGS = window.TOTAL_STRINGS = 100000;

function getRandomInt(max) {
  return Math.floor(Math.random() * max);
}

function makeRandomString(len) {
  var text = "";
  for( var i=0; i < len; i++ ) {
    text += possible.charAt(getRandomInt(possible.length));
  }
  return text;
}

while (data.length < TOTAL_STRINGS) {
  data.push(makeRandomString(getRandomInt(20)));
}

Tests:

startsWith
var x = 0; var TOTAL_STRINGS = window.TOTAL_STRINGS; var data = window.data; var regex = window.regex; while (x < TOTAL_STRINGS) { const str = data[x]; str.endsWith("9"); x += 1; }
.charAt
var x = 0; var TOTAL_STRINGS = window.TOTAL_STRINGS; var data = window.data; var match = window.match; while (x < TOTAL_STRINGS) { const str = data[x]; str.charAt(TOTAL_STRINGS - 1) === '9'; x += 1; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
startsWith
.charAt

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 10 months ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/138.0.0.0 Safari/537.36

Browser/OS: Chrome 138 on Windows

View result in a separate tab

Test name	Executions per second
startsWith	1766.0 Ops/sec
.charAt	6905.7 Ops/sec

Autogenerated LLM Summary (model llama3.2:3b, generated one year ago):

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark and explain what's being tested.

**Benchmark Overview**

The benchmark is designed to compare the performance of two approaches: `endsWith` and `.charAt`. The test is focused on measuring which approach is faster when checking if a string ends with a specific character, in this case, '9'.

**Script Preparation Code**

The provided script preparation code generates an array of random strings (`data`) using a combination of uppercase letters, lowercase letters, digits, and special characters. This is done to create a large dataset for the benchmark.

**Html Preparation Code**

The HTML preparation code consists of a simple `<div>` element, which is not directly related to the performance test being run.

**Individual Test Cases**

There are two individual test cases:

1. **".endsWith"**: This test case checks if each string in the `data` array ends with '9' using the `endsWith` method.
2. **".charAt"`: This test case checks if each string in the `data` array has the character at its last index (i.e., the character that would be accessed by indexing the string with `TOTAL_STRINGS - 1`) equal to '9' using the `.charAt()` method.

**Comparison of Approaches**

The two approaches being compared are:

* **.endsWith**: This method checks if a string ends with a specific substring (in this case, '9'). It is a relatively fast and efficient way to perform this type of check.
* **.charAt**: This method accesses the last character of a string by indexing it with `TOTAL_STRINGS - 1`. While this approach can be fast for accessing individual characters in a string, it may not be as efficient as using `endsWith` when checking if a string ends with a specific substring.

**Pros and Cons**

* **.endsWith**:
	+ Pros: Efficient for checking if a string ends with a specific substring.
	+ Cons: May have additional overhead due to the use of a loop or recursive function calls (not explicitly shown in the benchmark code).
* **.charAt**:
	+ Pros: Can be fast for accessing individual characters in a string.
	+ Cons: May not be as efficient for checking if a string ends with a specific substring, as it involves indexing into the string.

**Library and Special JS Features**

There is no explicit mention of any libraries or special JavaScript features being used in this benchmark. The code appears to only use built-in JavaScript methods and functionality.

**Other Alternatives**

If you're looking for alternative approaches to checking if a string ends with a specific substring, some options might include:

* Using regular expressions (e.g., ` RegExp.test()`)
* Utilizing a library like Lodash's `endsWith()` function
* Implementing a custom loop-based approach using the `indexOf()` method

Keep in mind that the choice of approach will depend on the specific requirements and constraints of your use case.

Related benchmarks:

.endsWith vs .charAt for single char (version: 0)

Testing some things

Comparing performance of: startsWith vs .charAt

Created: 6 years ago by: Guest

Jump to the latest result

startsWith

.charAt

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated one year ago):