Benchmark: .startsWith() vs .test() vs .match() vs .indexOf() vs equality

Script Preparation code:

var html = "https://www.google.com";

Tests:

regexp .test()
/^https?:\/\//.test(html)
string .match()
!!html.match(/^https:\/\//)
indexOf === 0
html.indexOf('https://') === 0
string .startsWith()
html.startsWith('https://')
Equality
html[0] === 'h' && html[1] === 't' && html[2] === 't' && html[3] === 'p' && html[4] === 's' && html[5] === ':' && html[6] === '/' && html[7] === '/'

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
regexp .test()
string .match()
indexOf === 0
string .startsWith()
Equality

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 26 days ago):

LLMs can make mistakes. Check important info.

Let's break down what is being tested in this benchmark, along with the pros and cons of each approach.

**What is being tested:**

This benchmark compares the performance of four different methods to check if a given string starts with a specific substring:

1. `RegExp.test()`
2. `String.match()` (note that the regex pattern is implicit and only checks for a literal match, not a start-of-string match)
3. `indexOf === 0` (which calls the `indexOf()` method on the string, returning the index of the first occurrence of the substring, or -1 if not found)
4. Manual equality check using indexing (`html[0] === 'h' && ...`)

**Options compared:**

The benchmark compares the performance of these four methods to determine which one is the fastest.

**Pros and Cons:**

1. **RegExp.test()**: This method is more flexible than the others, as it can be used with any regex pattern, not just a literal substring. However, it may be slower due to the overhead of compiling a regular expression.
2. **String.match()**: As mentioned earlier, this method only checks for a literal match, not a start-of-string match. It's also less flexible than RegExp.test().
3. **indexOf === 0**: This method is simple and lightweight, but may be slower due to the overhead of calling the `indexOf()` method on the string.
4. **Manual equality check**: This approach can be slow if the substring is not found in the string, as it requires checking every character.

**Other considerations:**

* The use of a literal substring (`"https://"` ) simplifies the benchmarking process but may not reflect real-world usage scenarios where substrings are often more complex.
* The `html` variable is set to a hardcoded URL, which may not represent a typical user input scenario. In a real-world application, the input string would likely be dynamic.

**Library:**

None of the libraries are explicitly mentioned in this benchmark definition, but it's worth noting that using libraries like jQuery or Lodash can introduce additional overhead and affect performance.

No special JavaScript features or syntax are being tested in this benchmark.

As for alternatives, other methods to check if a string starts with a specific substring include:

* Using `startsWith()` (introduced in ECMAScript 2015)
* Regular expressions with the `^` anchor
* Manual indexing and comparison using array notation (like `html[0] === 'h' && ...`)
* String manipulation functions like `substr()` or `substring()`

These alternatives can be tested using a similar benchmarking approach to measure their performance.

Latest run results:

Run details: (Test run date: one year ago)

User agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/116.0.0.0 Safari/537.36

Browser/OS: Chrome 116 on Linux

View result in a separate tab

Test name	Executions per second
regexp .test()	6769995.0 Ops/sec
string .match()	5276054.0 Ops/sec
indexOf === 0	11098094.0 Ops/sec
string .startsWith()	5732419.5 Ops/sec
Equality	1259133.1 Ops/sec

Related benchmarks:

.startsWith() vs .test() vs .match() vs .indexOf() vs equality (version: 0)

Comparing performance of: regexp .test() vs string .match() vs indexOf === 0 vs string .startsWith() vs Equality

Created: one year ago by: Guest

Jump to the latest result

regexp .test()

string .match()

indexOf === 0

string .startsWith()

Equality

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 26 days ago):