Benchmark: indexOf vs map vs map2

Script Preparation code:

var array = [];
for (var i=0; i<300; ++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;
}

var map2 = new Map();
array.forEach(item => map2.set(item, true));

function hasWithMap2(needle) {
	return map2.has(needle);
}

Tests:

indexOf
for (var i=0; i<100; ++i) { hasWithIndexOf('404'); }
map
for (var i=0; i<100; ++i) { hasWithMap('404'); }
map2
for (var i=0; i<100; ++i) { hasWithMap2('404'); }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
indexOf
map
map2

Fastest: N/A

Slowest: N/A

Latest run results:

No previous run results

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

LLMs can make mistakes. Check important info.

**Benchmark Explanation**

The provided benchmark compares the performance of three different approaches to check if an element exists in an array:

1. `indexOf`: Uses the `Array.prototype.indexOf()` method, which returns the index of the first occurrence of the specified value. If the value is not found, it returns -1.
2. `map`: Uses the `Array.prototype.forEach()` method with a callback function that checks if the current element exists in an object (created by calling `Array.prototype.forEach()` on the array).
3. `map2`: Uses the `Map` data structure, which allows for efficient lookups using the `has()` method.

**Options Compared**

The benchmark compares the performance of these three approaches:

* `indexOf`
* `map`
* `map2`

**Pros and Cons of Each Approach**

1. **`indexOf`**:
	* Pros: Simple and widely supported.
	* Cons: Can be slow for large arrays, as it has to iterate through the entire array to find the index.
2. **`map`**:
	* Pros: Can be efficient if the object is already cached or reused, but requires additional memory overhead.
	* Cons: Can be slower than `indexOf` for very large arrays, and may not be suitable for scenarios where the object needs to be recreated on every iteration.
3. **`map2`**:
	* Pros: Efficient lookups using the `has()` method, and can handle large datasets without significant performance degradation.
	* Cons: Requires a `Map` data structure, which may add additional memory overhead.

**Library and Purpose**

The `Array.prototype.forEach()` method is used with an object to create a cached lookup table. The purpose of this approach is to enable efficient lookups using the `has()` method.

**Special JS Feature or Syntax**

None mentioned in the provided benchmark definition. However, it's worth noting that the use of `var` and `let` variables is not explicitly prohibited in JavaScript, but it's generally considered good practice to use `let` for variable declarations to avoid variable hoisting issues.

**Other Alternatives**

1. **Using `Array.prototype.includes()`**: This method is a more modern alternative to `indexOf()`, which returns the index of the first occurrence of the specified value, or -1 if not found. It's generally faster and more efficient than `indexOf()`.
2. **Using `Set` data structure**: Similar to `Map`, but with faster lookup times for elements that are added multiple times.
3. **Native `Array.prototype.includes()` implementation**: Some browsers (like Chrome) have a native implementation of the `includes()` method, which can provide better performance than using the `indexOf()` method or creating an object for caching.

These alternatives may not be included in the benchmark definition, but they are worth considering when evaluating the performance of different approaches.

Related benchmarks:

indexOf vs map vs map2 (version: 0)

Comparing performance of: indexOf vs map vs map2

Created: 4 years ago by: Guest

Jump to the latest result

indexOf

map

map2

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):