Benchmark: indexOf VS includes in JavaScript Array

Script Preparation code:

var array = [4457, 6563, 30851, 40303, 42053, 47405, 52810, 90772, 96252, 125488, 151673, 158557, 178050, 195190, 203029, 210539, 216541, 242156, 262560, 275861, 284045, 285385, 286899, 307581, 337018, 340978, 353359, 365569, 398211, 398284, 424423, 425550, 427665, 429594, 440844, 445754, 452877, 491428, 494809, 501187, 513180, 518540, 520189, 527068, 532607, 537414, 541551, 543608, 544796, 548722, 564979, 569266, 586233, 589433, 604742, 628230, 649872, 651744, 657815, 663902, 669333, 676214, 684405, 705674, 706487, 709528, 728070, 728490, 729012, 741404, 742443, 750860, 760686, 783419, 791554, 797225, 799311, 813491, 816277, 822413, 844859, 865342, 869820, 871814, 873451, 873918, 879036, 882069, 902231, 918049, 918788, 920500, 930129, 932809, 943528, 943818, 964607, 974967, 995708, 999756];

Tests:

indexOf
array.indexOf(151673);
includes
array.includes(151673);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
indexOf
includes

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/130.0.0.0 Safari/537.36

Browser/OS: Chrome 130 on Linux

View result in a separate tab

Test name	Executions per second
indexOf	5096661.5 Ops/sec
includes	5081301.0 Ops/sec

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

LLMs can make mistakes. Check important info.

I'll break down the provided benchmark JSON and explain what's being tested, compared, and its implications.

**Benchmark Definition**

The benchmark is designed to measure the performance difference between two JavaScript methods: `indexOf` and `includes`. Both methods are used to find a specific value within an array. The script preparation code creates a large array of numbers and the test cases use this array.

**Test Cases**

There are two test cases:

1. **indexOf**: This test case uses the `indexOf` method to find the index of a specific number (151673) in the array.
2. **includes**: This test case uses the `includes` method to check if a specific number (151673) is present in the array.

**Comparison**

The comparison between `indexOf` and `includes` is based on their performance, measured by the number of executions per second.

**Options Compared**

Two options are being compared:

1. **Array.indexOf()**: A method that returns the index of a specified value within an array.
2. **Array.includes()**: A method that checks if a value exists in an array (including its presence at any position).

**Pros and Cons of Each Approach:**

*   **`indexOf()`**:
    *   Pros:
        *   Returns the actual index of the found value, which can be useful for iterating over arrays.
        *   Can provide early exit when the value is not present in the array, reducing unnecessary iterations.
    *   Cons:
        *   May perform slower due to its iterative nature and potential cache misses.
*   **`includes()`**:
    *   Pros:
        *   Faster than `indexOf()` since it uses a more efficient algorithm that skips over unnecessary elements.
        *   Provides early exit when the value is not present in the array, reducing unnecessary iterations.
    *   Cons:
        *   Returns a boolean result instead of the actual index, which might be less useful for some use cases.

**Library:**

There is no explicit library mentioned in this benchmark. Both `indexOf` and `includes` are native JavaScript methods built into the language.

**Special JS Feature or Syntax:**

No special JavaScript features or syntaxes are used in these test cases.

**Other Considerations:**

When choosing between `indexOf` and `includes`, consider the following:

*   If you need to find the actual index of a value, use `indexOf()`.
*   If you only care about whether a value is present in the array (e.g., for faster equality checks), use `includes()`.

**Alternatives:**

Some alternative approaches for finding specific values within arrays include:

1.  **`findIndex()`**: Returns the index of the first occurrence of the specified value, similar to `indexOf()`.
2.  **Array.prototype.findIndex()`: A more concise and readable way to find the index of a value using an arrow function.
3.  **Binary Search**: If you know the range of values in the array (e.g., integers between 1 and n), binary search can be more efficient than linear searches like `indexOf()` or `includes()`.

Related benchmarks:

indexOf VS includes in JavaScript Array (version: 0)

Comparing performance of: indexOf vs includes

Created: 3 years ago by: Guest

Jump to the latest result

indexOf

includes

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):