Benchmark: indexOf vs map 002-5

Script Preparation code:

var array = [];
for (var i=0; i<5; ++i) {
  	array.push('00' + i);
}

function hasWithIndexOf(needle) {
	return array.indexOf(needle) !== -1;
}

var map = {};
array.forEach(item => map[item] = true);

function hasWithMap(needle) {
	return needle in map;
}

Tests:

indexOf
for (var i=0; i<100; ++i) { array.indexOf("404") !== -1; // array.indexOf("000") !== -1; }
map
for (var i=0; i<100; ++i) { const x = "404" in map }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
indexOf
map

Fastest: N/A

Slowest: N/A

Latest run results:

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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 MeasureThat.net and explore what's being tested in this benchmark.

**Benchmark Definition:**

The provided JSON represents a JavaScript microbenchmark that compares the performance of two approaches:

1. `indexOf` (also known as "hasWithIndexOf")
2. `map` (also known as "in" operator)

The benchmark definition creates an array with 5 elements, each representing a string in the format "00x", where x is an integer from 0 to 4.

**Script Preparation Code:**

This code prepares the array and defines two functions:

* `hasWithIndexOf(needle)`: Returns `true` if `needle` exists in the array using the `indexOf` method.
* `map`: Creates a new object `map` and uses the `forEach` method to iterate over the array, assigning each element as a key in the map with a value of `true`.

The benchmark then tests both functions by iterating 100 times and checking if "404" or "000" exists in the array using the respective functions.

**Comparison:**

The comparison is between the two approaches:

1. `indexOf`: Uses the `indexOf` method to check for existence.
2. `map`: Uses the "in" operator (also known as the bracket notation) to check for existence.

**Pros and Cons:**

* `indexOf`:
	+ Pros: Simple, widely supported, and fast.
	+ Cons: Can be slow if the array is very large, as it performs a linear search.
* `map`: 
	+ Pros: Faster than `indexOf` for larger arrays, as it uses a hash table lookup.
	+ Cons: May not work in older browsers or with certain types of data structures.

**Library and Purpose:**

The "in" operator (also known as bracket notation) is a built-in JavaScript feature that allows you to check if a property exists in an object. It's often used for membership testing, but can also be used for array lookups.

**Special JS Feature or Syntax:**

This benchmark doesn't use any special JavaScript features or syntax beyond what's built into the language.

**Alternatives:**

Other alternatives for performing existence checks include:

1. `includes()`: A modern method introduced in ECMAScript 2019 that provides a more readable and efficient way to check if an array includes a value.
2. Using a library like Lodash or Underscore.js, which provide optimized implementations of various algorithms, including membership testing.

**Other Considerations:**

When writing microbenchmarks, it's essential to consider factors such as:

1. Input size: The benchmark is designed to test performance on small arrays. For larger datasets, the results might be skewed.
2. Browser and engine variations: MeasureThat.net tests across various browsers and engines, which can affect the outcome.
3. Edge cases: Ensure that the benchmark covers a range of scenarios, including edge cases like empty arrays or null values.

By understanding these factors and approaches, you'll be better equipped to write effective microbenchmarks that provide valuable insights into JavaScript performance.

Related benchmarks:

indexOf vs map 002-5 (version: 0)

Comparing performance of: indexOf vs map

Created: 2 years ago by: Guest

Jump to the latest result

indexOf

map

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):