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startsWith or regex test
(version: 0)
Comparing performance of:
startsWith vs regex
Created:
2 years ago
by:
Guest
Go to the latest result
Script Preparation code:
window.myString = "Hello, world!"; window.prefix = "Hello"; window.regex = /^Hello/;
Tests:
startsWith
if (myString.startsWith(prefix)) { // do something }
regex
if (regex.test(myString)) { // do something }
Rendered benchmark preparation results:
Suite status:
<idle, ready to run>
Run tests (2)
Previous results
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Test case name
Result
startsWith
regex
Fastest:
N/A
Slowest:
N/A
Latest run results:
Run details:
(Test run date:
2 years ago
)
User agent:
Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/119.0.0.0 Safari/537.36
Browser/OS:
Chrome 119 on Linux
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<iframe src="https://measurethat.net/Embed?id=488200" width="100%" height="500px"></iframe>
startsWith
6.4M/s
regex
6.3M/s
View exact numbers
Test name
Executions per second
✓
startsWith
6,394,742 Ops/sec
regex
6,338,390 Ops/sec
Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
Let's break down the benchmark definition and test cases to understand what is being tested. **Benchmark Definition** The provided JSON defines a benchmark named "startsWith or regex test". The description is null, which means there isn't any additional context about the benchmark. However, the script preparation code sets up two variables: * `window.myString`: a string literal with the value `"Hello, world!"`. * `window.prefix`: another string literal with the value `"Hello"`. * `window.regex`: a regular expression object with the value `/^Hello/`. The purpose of these variables is to create a test scenario where two different approaches are compared: 1. **startsWith**: This approach checks if the `myString` starts with the `prefix` using the `startsWith()` method. 2. **regex**: This approach uses a regular expression to match the `myString` against the `/^Hello/` pattern. **Options being compared** The two options being compared are: 1. **Regular string comparison (`startsWith()`)**: This is a simple and efficient way to check if one string starts with another. 2. **Regular expression matching**: This approach uses a regular expression to match the `myString` against a specific pattern. Regular expressions can be powerful tools for pattern-matching, but they can also be slower than simple string comparisons. **Pros and Cons of each approach** **startsWith()** Pros: * Fast: String comparison is generally fast. * Efficient: This approach doesn't require creating a regular expression object or compiling the regex pattern. Cons: * May not work as expected for non-ASCII characters or Unicode characters that don't start with the prefix. * May be slower than using regular expressions if the prefix is longer than the `myString`. **Regular Expression Matching** Pros: * Flexible: Regular expressions can match a wide range of patterns, including non-string data types like numbers and dates. * Powerful: Regular expressions can perform complex pattern-matching, such as matching strings within strings or extracting specific parts of a string. Cons: * Slower: Creating and compiling regular expression objects can be slower than simple string comparisons. * Less readable: Complex regular expression patterns can be difficult to read and understand. **Library used** In this benchmark, the `regex` option uses the built-in JavaScript `test()` method, which is a part of the ECMAScript standard. The `test()` method takes two arguments: the string to test against the regex pattern, and the regex pattern itself. **Special JS feature or syntax** None are mentioned in this benchmark definition. Now, let's look at the individual test cases: 1. **Test Case 1: "startsWith"** This test case runs the `if (myString.startsWith(prefix))` code multiple times to measure its performance. 2. **Test Case 2: "regex"** This test case runs the `if (regex.test(myString))` code multiple times to measure its performance. **Alternative approaches** If you want to use a different approach, here are some alternatives: * Use a different string comparison method, such as using the `localeCompare()` method or the `indexOf()` method. * Use a more complex regular expression pattern, such as one that uses character classes or anchors. * Use a different library or framework for regular expression matching, such as jQuery's `regex` function. Note that these alternative approaches may have different performance characteristics and trade-offs compared to the original benchmark.
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