Benchmark: javascript startsWith() vs includes() for longer string

Tests:

startsWith
const str = "utm_source_dfsdfsd__dfsdfsd_dfsdfsd_aaaaaavdfgdfgf!" str.startsWith("utm_")
includes
const str = "utm_source_dfsdfsd__dfsdfsd_dfsdfsd_aaaaaavdfgdfgf" str.includes("utm_")

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
startsWith
includes

Fastest: N/A

Slowest: N/A

Latest run results:

No previous run results

This benchmark does not have any results yet. Be the first one to run it!

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 on MeasureThat.net.

**What is being tested?**

The provided JSON represents two individual test cases, each comparing different approaches to check if a string starts with or contains a specific substring. The tests are:

1. `startsWith`: checks if the string "str" starts with the substring "utm_".
2. `includes`: checks if the string "str" includes the substring "utm_".

**Options compared:**

In this case, there are only two options being compared:

1. `startsWith()`
2. `includes()` (which is typically a method on the String object in JavaScript)

These two methods have different performance characteristics and use cases.

**Pros and Cons of each approach:**

1. `startsWith()`: This method has an O(n) time complexity, where n is the length of the string. It iterates through the string to find the first occurrence of the specified substring.
	* Pros:
		+ Fast for short substrings
		+ Simple implementation
	* Cons:
		+ Slow for long substrings
		+ May be slower than `includes()` for certain browser implementations
2. `includes()`: This method has a different implementation, which is typically based on the Boyer-Moore algorithm or similar string searching algorithms.
	* Pros:
		+ Fast for both short and long substrings
		+ Often faster than `startsWith()` for certain use cases
	* Cons:
		+ May have more complex implementation compared to `startsWith()`
		+ Can be slower for very short strings

**Library usage:**

In this case, there is no explicit library mentioned in the benchmark definition or the test cases. However, it's worth noting that some browsers may use additional libraries or built-in methods to optimize string matching.

**Special JavaScript features/syntax:**

None are explicitly mentioned in this example. If you'd like me to explain more about other JavaScript features or syntax, feel free to ask!

**Other alternatives:**

If you're looking for alternative approaches to these methods, here are a few:

1. `substring()` and comparison operators (`===`): You can use the `substring()` method to extract a substring from the original string and then compare it using equality operators.
2. Regular expressions (`RegExp`): You can use regular expressions to match the specified substring against the entire string.
3. Custom implementation: Depending on your specific requirements, you might want to implement your own custom algorithm for matching substrings.

For most use cases, `startsWith()` or `includes()` are suitable choices, but understanding the pros and cons of each approach can help you optimize your code for better performance.

Related benchmarks:

javascript startsWith() vs includes() for longer string (version: 0)

Comparing performance of: startsWith vs includes

Created: 4 years ago by: Guest

Jump to the latest result

startsWith

includes

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):