Benchmark: Javascript string.endsWith vs string.slice and triple equal 2

Script Preparation code:

function compareEndsWith(val, comparator) {
  return val.endsWith(comparator)
}
function compareEndsWith2(val, comparator) {
  return val.endsWith(comparator, comparator.length)
}
function compareSliceMethod(val, comparator) {
  const thingToCompare = val.slice(-comparator.length)
  return thingToCompare === comparator
}

Tests:

endWith
const value = Math.random().toString().padEnd(20,'0'); const ending = "asdf" compareEndsWith(value, ending)
slice
const value = Math.random().toString().padEnd(20,'0'); const ending = "asdf" compareSliceMethod(value, ending)
endsWith2
const value = Math.random().toString().padEnd(20,'0'); const ending = "asdf" compareEndsWith2(value, ending)

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
endWith
slice
endsWith2

Fastest: N/A

Slowest: N/A

Latest run results:

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

LLMs can make mistakes. Check important info.

Let's dive into the world of JavaScript microbenchmarks.

**What is being tested?**

The provided benchmark tests three different approaches for determining whether a string ends with a specific substring:

1. `compareEndsWith`: This function uses the `endsWith` method, which checks if the end of a string matches a specified value.
2. `compareEndsWith2`: This function also uses the `endsWith` method, but it takes an additional argument specifying the length of the substring to match.
3. `compareSliceMethod`: This function slices the last `comparator.length` characters from the input string and then compares them directly with the comparator.

**Options being compared**

The three approaches are being tested against each other to determine which one is the fastest.

**Pros and Cons:**

* **`compareEndsWith`**: Pros: Simple and intuitive. Cons: May be slower if the substring is not found at the end of the string.
* **`compareEndsWith2`**: Pros: Reduces overhead by passing the length of the comparator as an argument. Cons: May require more memory allocation due to the additional parameter.
* **`compareSliceMethod`**: Pros: Can be faster for shorter substrings, as it avoids the overhead of `endsWith`. Cons: Requires slicing the string, which can be slower for large strings.

**Library usage**

None of the test cases explicitly use any external libraries. However, it's worth noting that the `padEnd` method used in the benchmark preparation code is a part of the ECMAScript standard and is supported by most modern browsers.

**Special JavaScript feature or syntax**

The only notable feature used in this benchmark is the use of `Math.random().toString().padEnd(20,'0')`, which generates a random string with 20 leading zeros. This is done to ensure that the comparison substrings (`"asdf"` and the sliced strings) have different lengths, making it more representative of real-world scenarios.

**Other alternatives**

If you wanted to test alternative approaches for determining whether a string ends with a specific substring, some options could include:

* Using regular expressions (e.g., `new RegExp('.*' + ending)`).
* Implementing a custom loop that iterates over the characters of the string.
* Using a library like `lodash` or `string-polyfill`, which provides optimized implementations for various string manipulation methods.

Keep in mind that these alternatives might have different performance characteristics and may not be as representative of real-world scenarios.

Related benchmarks:

Javascript string.endsWith vs string.slice and triple equal 2 (version: 0)

Comparing performance of: endWith vs slice vs endsWith2

Created: 3 years ago by: Guest

Jump to the latest result

endWith

slice

endsWith2

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

No previous run results

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