Benchmark: for vs foreach vs some vs every vs for..of vs map with mutation

Script Preparation code:

var array = new Array(100);

Tests:

for
for (var i = 0; i < array.length; i++) { array[i] = 2; }
foreach
array.forEach(function(i) { array[i] = 2; });
some
array.some(function(i) { array[i] = 2; });
every
array.every(function(i) { array[i] = 2; });
for..of
for (var i of array) { array[i] = 2; }
map
array.map(a => a);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
for
foreach
some
every
for..of
map

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.

Measuring the performance of different JavaScript loops is an essential task in understanding the language's nuances and optimizing code for various browsers and devices.

**Loop Types Compared**

The benchmark compares six different loop types:

1. **Traditional `for` loop**: This is a classic, explicit loop that uses a counter variable to iterate over an array.
2. **`forEach` method**: Introduced in ECMAScript 5, this method provides a more concise way to iterate over arrays using a callback function.
3. **`some` method**: Another iteration method, `some` returns `true` if at least one element passes the test provided by the callback function.
4. **`every` method**: Similar to `some`, but returns `true` only if all elements pass the test.
5. **`for...of` loop**: A new, more modern loop that uses a simple syntax for iterating over arrays and other iterable objects.
6. **`map` method with mutation**: The `map` method creates a new array by applying a transformation to each element, but this benchmark modifies the original array.

**Pros and Cons of Each Approach**

Here's a brief overview of the pros and cons of each loop type:

1. **Traditional `for` loop**:
	* Pros: Easy to understand, flexible, and works well for complex logic.
	* Cons: Can be verbose, and the loop counter can lead to off-by-one errors.
2. **`forEach` method**:
	* Pros: Concise, easy to read, and modern syntax.
	* Cons: May not perform as well as traditional loops due to function call overhead.
3. **`some` and `every` methods**:
	* Pros: Efficient for short iterations or when only one value is needed.
	* Cons: May be less readable than other loop types, and can lead to confusion if used incorrectly.
4. **`for...of` loop**:
	* Pros: Modern syntax, easy to understand, and efficient for simple iterations.
	* Cons: Limited control over iteration logic compared to traditional loops.
5. **`map` method with mutation**:
	* Pros: Creates a new array, avoiding side effects and preserving original data.
	* Cons: May lead to performance overhead due to memory allocation and copying.

**Library Usage**

The `forEach`, `some`, and `every` methods are built-in JavaScript methods that don't require any external libraries. They are part of the ECMAScript standard and are supported by most modern browsers.

**Special JS Features or Syntax**

None of the loops in this benchmark rely on special JavaScript features or syntax, such as async/await, Promises, or Generators.

**Alternatives**

Other loop types or alternatives might be considered depending on specific use cases:

* **`while` loop**: A more traditional loop that uses a conditional statement to control iteration.
* **`do...while` loop**: Similar to the `for` loop but with a different initialization order.
* **`reduce` method**: Used for reducing an array to a single value, often with accumulate state.

For most use cases, understanding and comparing these six loop types should provide sufficient insight into optimizing JavaScript code for various browsers and devices.

Related benchmarks:

for vs foreach vs some vs every vs for..of vs map with mutation (version: 0)

Compare loop performance

Comparing performance of: for vs foreach vs some vs every vs for..of vs map

Created: 5 years ago by: Guest

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for

foreach

some

every

for..of

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):