var string = "Hello world!";
var regex = /Hello/;
regex.test(string);
string.includes("Hello");
string.match("Hello");
string.startsWith("Hello");
--enable-precise-memory-info
flag.
Test case name | Result |
---|---|
RegEx.test | |
String.includes | |
String.match | |
String.startsWith |
Test name | Executions per second |
---|---|
RegEx.test | 5568804.5 Ops/sec |
String.includes | 8018066.0 Ops/sec |
String.match | 3985646.8 Ops/sec |
String.startsWith | 8293765.5 Ops/sec |
Let's break down the provided benchmark and explain what's being tested, along with the pros and cons of each approach.
Benchmark Overview
The provided benchmark compares the performance of four string manipulation functions:
String.startsWith
String.includes
RegExp.test
These functions are used to check if a given string contains a specific pattern or sequence of characters.
Options Being Compared
Here's what's being compared for each function:
String.startsWith
vs String.includes
: Both functions check if the input string starts with a specified prefix. However, String.startsWith
is more efficient because it stops searching as soon as it finds the match.RegExp.test
vs other two options: RegExp.test
is a more general-purpose function that can be used to test for any pattern, not just prefixes or substrings.Pros and Cons
String.startsWith
String.includes
String.startsWith
, may use more CPU cycles to search for the match.RegExp.test
Library and Purpose
In this benchmark, RegExp
is being used to create regular expressions (regex = /Hello/;
). The RegExp.test
function uses these regular expressions to check if the input string matches the pattern.
Special JS Feature or Syntax
There isn't any special JavaScript feature or syntax mentioned in this benchmark. However, it's worth noting that modern JavaScript engines have optimized implementations of these functions, which can affect performance.
Other Alternatives
Other alternatives for checking prefix or substring matches could be:
indexOf()
: A built-in method that searches for the specified value within a string and returns its index.lastIndexOf()
: Similar to indexOf
, but searches from the end of the string instead.Keep in mind that these methods may have different performance characteristics compared to String.startsWith
and String.includes
.