Benchmark: indexOf vs startsWith for markers

Script Preparation code:

var text = '<!-- jsx --><div><div>foobar</div><div>foobar</div><div>foobar</div></div>'
var marker = '<!-- jsx -->'

Tests:

indexOf
text.indexOf(marker)
indexOf (specifically at the start of the string)
text.indexOf(marker) === 0
startsWith
text.startsWith(marker)

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
indexOf
indexOf (specifically at the start of the string)
startsWith

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/96.0.4664.110 Safari/537.36

Browser/OS: Chrome 96 on Windows

View result in a separate tab

Test name	Executions per second
indexOf	7007105.5 Ops/sec
indexOf (specifically at the start of the string)	7047941.5 Ops/sec
startsWith	6262066.5 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's dive into the world of JavaScript microbenchmarks!

**What is being tested?**

The provided JSON benchmark tests two string methods: `indexOf` and `startsWith`. Specifically, it compares the performance of these two methods when used to search for a substring within a larger string.

**Options compared:**

1. `indexOf`: Returns the index of the first occurrence of the specified value in the string.
2. `startsWith`: Returns `true` if the string starts with the specified value, or `false` otherwise.

**Pros and Cons:**

* **`indexOf`**:
	+ Pros:
		- Widely supported across browsers and platforms.
		- Can be used to search for a substring anywhere in the string, not just at the beginning.
	+ Cons:
		- May require more computations if the substring is not found at the beginning of the string.
		- Can be slower than `startsWith` due to its broader search capabilities.
* **`startsWith`**:
	+ Pros:
		- Generally faster than `indexOf` because it only checks the first few characters of the string.
		- More suitable for searching substrings at the beginning of a string.
	+ Cons:
		- May not be supported across all browsers and platforms (it's a relatively modern feature).
		- Less versatile than `indexOf`, as it only searches for substrings starting from the beginning.

**Library:**

None. This benchmark does not use any external libraries.

**Special JS feature or syntax:**

`startsWith` is a relatively recent addition to JavaScript (introduced in ECMAScript 2015) and may require support for modern browsers or versions of Node.js.

**Benchmark preparation code:**

The script prepares the test string by concatenating three identical `<div>foobar</div>` elements inside a `<div>`, and then defines a marker substring (``).

**Other alternatives:**

If you want to compare other string methods, such as:

* `includes`: Returns `true` if the string includes the specified value, or `false` otherwise.
* `endsWith`: Returns `true` if the string ends with the specified value, or `false` otherwise.

You can add more benchmark cases to the test array. For example:
```json
{
    "Benchmark Definition": "text.includes(marker)",
    "Test Name": "includes"
},
{
    "Benchmark Definition": "text.endsWith(marker)",
    "Test Name": "endsWith"
}
```
Keep in mind that each additional benchmark case will require more preparation code and may increase the overall complexity of the test.

Related benchmarks:

indexOf vs startsWith for markers (version: 0)

Comparing performance of: indexOf vs indexOf (specifically at the start of the string) vs startsWith

Created: 3 years ago by: Guest

Jump to the latest result

indexOf

indexOf (specifically at the start of the string)

startsWith

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):