Benchmark: Array.indexOf vs String.indexOf

Script Preparation code:

var a = ['ff1234567890121', 'ff1234567890122', 'ff1234567890123', 'ff1234567890124', 'ff1234567890125'];
var s = '-ff1234567890121--ff1234567890122--ff1234567890123--ff1234567890124--ff1234567890125-';
var t = 'ff1234567890124';

Tests:

Array indexOf
var i = a.indexOf(t);
String indexOf
var i = s.indexOf('-' + t + '-');

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Array indexOf
String indexOf

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/135.0.0.0 Safari/537.36

Browser/OS: Chrome 135 on Windows

View result in a separate tab

Test name	Executions per second
Array indexOf	32685136.0 Ops/sec
String indexOf	52195964.0 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down the benchmark and explain what's being tested.

**Benchmark Overview**

The benchmark compares the performance of two JavaScript functions: `Array.indexOf()` and `String.indexOf()`. Both functions are used to find the index of a specified value in an array or string, respectively.

**Options Compared**

The benchmark tests two different approaches:

1. **Array.indexOf()**: This function is part of the ECMAScript standard and returns the index of the first occurrence of the specified value in the array.
2. **String.indexOf()**: This function is also part of the ECMAScript standard and returns the index of the first occurrence of the specified value in the string.

**Pros and Cons**

Here are some pros and cons of each approach:

* **Array.indexOf()**:
	+ Pros: Can be used with arrays, relatively simple implementation.
	+ Cons: May have a higher overhead due to its use of a linear search algorithm, which can lead to slower performance for large datasets.
* **String.indexOf()**:
	+ Pros: Often faster than `Array.indexOf()` due to optimized implementations in browsers and engines. Also, it can be used with strings, not just arrays.
	+ Cons: May have a higher overhead due to its use of a linear search algorithm, which can lead to slower performance for large datasets.

**Library Used**

None in this benchmark. The `Array.indexOf()` and `String.indexOf()` functions are part of the ECMAScript standard.

**Special JS Features or Syntax**

There are no special JavaScript features or syntax used in this benchmark that would require expertise beyond basic knowledge of JavaScript.

**Other Considerations**

When choosing between these two approaches, consider the following:

* If you're working with arrays and need to find an element quickly, `Array.indexOf()` might be a good choice.
* If you're working with strings and need to find a substring or character, `String.indexOf()` might be a better option.

**Alternatives**

Other alternatives for searching in JavaScript include:

* Using regular expressions (`RegExp.test()`, `RegExp.exec()`), which can provide more flexibility but may also introduce overhead.
* Using the `some()` and `findIndex()` methods, which are more functional programming-friendly but may have different performance characteristics.
* Using optimized libraries like `lodash` or `underscore`, which provide their own implementations of search functions.

Keep in mind that these alternatives might not be directly comparable to `Array.indexOf()` and `String.indexOf()`, as they often involve different algorithmic approaches.

Related benchmarks:

Array.indexOf vs String.indexOf (version: 0)

Comparing performance of: Array indexOf vs String indexOf

Created: 8 years ago by: Guest

Jump to the latest result

Array indexOf

String indexOf

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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