Benchmark: substring vs endsWith

Script Preparation code:

var stringToCheck = '/asdasd/asdasd/asasd/asad/asdasd.html';
var stringToCheckLength = stringToCheck.length;
var stringToFind = '.html';
var stringToFindLength = 5;
var isStringFound = false;

Tests:

substring
if (stringToCheck.substring(stringToCheckLength - stringToFindLength) === stringToFind) { isStringFound = true; }
endsWith
if (stringToCheck.endsWith(stringToFind)) { isStringFound = true; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
substring
endsWith

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 3 years ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/88.0.4324.192 Safari/537.36

Browser/OS: Chrome 88 on Windows

View result in a separate tab

Test name	Executions per second
substring	1361941.8 Ops/sec
endsWith	2066171.8 Ops/sec

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

LLMs can make mistakes. Check important info.

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

**Benchmark Overview**

The benchmark compares the performance of two string manipulation methods: `substring` and `endsWith`. The tests aim to find the substring in the input string `stringToCheck` that matches a predefined length (`stringToFindLength`) and checks if it exists using both methods.

**Library Usage**

There is no explicit library usage mentioned in the JSON. However, since the benchmark involves string manipulation, we can assume that the JavaScript engine being tested provides built-in support for these operations.

**Special JS Features/Syntax**

There are no special JavaScript features or syntax used in this benchmark. The tests only involve standard JavaScript strings and methods.

**Benchmark Preparation Code**

The preparation code sets up two variables:

* `stringToCheck`: a sample string containing the substring to search.
* `stringToCheckLength`: the length of `stringToCheck`.
* `stringToFind`: the predefined substring length (`'.html'`).
* `stringToFindLength`: the actual length of `stringToFind` (5 characters).

The preparation code initializes a variable `isStringFound` to keep track of whether the string is found using either method.

**Test Cases**

There are two test cases:

1. **substring**: This test case checks if the substring in `stringToCheck` that matches `stringToFindLength` exists by calling `substring()` with the correct offset.
2. **endsWith**: This test case checks if the last part of `stringToCheck` (i.e., its length minus the length of `stringToFind`) matches `stringToFind` using the `endsWith()` method.

**Options Compared**

The benchmark compares the performance of two methods:

* `substring()`: calculates the offset for the substring by subtracting the desired length (`stringToFindLength`) from the total string length (`stringToCheckLength`). This approach is more explicit but may be slower due to the arithmetic operation.
* `endsWith()`: uses a built-in method that checks if the last character of the string matches the expected value. This approach might be faster because it avoids manual calculation.

**Pros and Cons**

**substring():**

Pros:

* More explicit, making the code easier to understand for some developers

Cons:

* May be slower due to arithmetic operation
* Requires manual calculation of offset

**endsWith():**

Pros:

* Typically faster due to built-in optimization
* Avoids manual calculation

Cons:

* Less explicit, which might make it harder for some developers to understand

**Other Considerations**

* The benchmark measures the number of executions per second (`ExecutionsPerSecond`) on a specific browser and device configuration.
* The test cases assume that the input string `stringToCheck` is not null or empty.

**Alternative Approaches**

If you wanted to add alternative approaches, you could consider testing:

1. Using regular expressions (regex) instead of manual calculation.
2. Using a library like Lodash's `endsWith()` method for comparison.
3. Comparing performance with other string manipulation methods, such as `indexOf()` or `startsWith()`.
4. Testing the impact of different JavaScript engine optimizations on performance.

These alternatives would require additional code and benchmark definitions to accommodate the changes.

Related benchmarks:

substring vs endsWith (version: 0)

Test substring vs endsWith where you have to calculate the length of the string for substring operation.

Comparing performance of: substring vs endsWith

Created: 3 years ago by: Guest

Jump to the latest result

substring

endsWith

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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