Benchmark: for w/length constant vs foreach vs some vs for..of (2)

Script Preparation code:

var array = new Array(100);

Tests:

for (lenght 另外儲存)
const length = array.length for (var i = 0; i < length; i++) { array[i]; }
foreach with operation
array.forEach(function(i) { array[i]; });
some
array.some(function(i) { array[i]; });
for..of
for (var i of array) { array[i]; }
for (lenght 不另外儲存)
for (var i = 0; i < array.length; i++) { array[i]; }

Historical Performance Data aggregated from 8 community runs

Desktop Results:

Chrome 8 runs

foreach with operation

4.3M/s

some

3.9M/s

for (lenght 另外儲存)

307K/s

for..of

247K/s

for (lenght 不另外儲存)

156K/s

Fastest: foreach with operation (27.4x faster)

View exact numbers

✓ foreach with operation: 4,281,616 ops/sec
• some: 3,929,353 ops/sec
• for (lenght 另外儲存): 306,928 ops/sec
• for..of: 247,221 ops/sec
• for (lenght 不另外儲存): 156,141 ops/sec

Results show median performance across all community submissions. Run this benchmark yourself to verify on your device.

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
for (lenght 另外儲存)
foreach with operation
some
for..of
for (lenght 不另外儲存)

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 2 years ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36

Browser/OS: Chrome 120 on Mac OS X 10.15.7

View result in a separate tab

foreach with operation

4.3M/s

some

4.3M/s

for (lenght 另外儲存)

295K/s

for..of

251K/s

for (lenght 不另外儲存)

157K/s

View exact numbers

Test name	Executions per second
✓ foreach with operation	4,302,686 Ops/sec
some	4,290,174 Ops/sec
for (lenght 另外儲存)	294,736 Ops/sec
for..of	250,573 Ops/sec
for (lenght 不另外儲存)	156,694 Ops/sec

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

LLMs can make mistakes. Check important info.

The provided JSON represents a benchmark test for comparing the performance of different loop constructs in JavaScript. The test is designed to measure the execution speed of four types of loops:

1.  **For Loop with Length Variable Storing**: This type of loop involves storing the length of the array in a variable and using that stored value as the condition in the loop.
2.  **For-each Loop (forEach)**: This type of loop uses the `forEach` method to iterate over the elements of the array, passing each element as an argument to a callback function.
3.  **Some Method**: This type of loop uses the `some` method to test whether at least one element in the array passes a provided test.
4.  **For-each Loop (for-of)**: This type of loop is similar to the previous one but is specified by the keyword "for...of".

**Options Compared**

The different loop constructs are compared based on their execution speed, measured in executions per second.

**Pros and Cons of Different Approaches**

1.  **For Loop with Length Variable Storing**: This approach can be beneficial when the array length needs to be accessed multiple times during the iteration.
    *   Pros: Can improve performance if the array length is frequently accessed.
    *   Cons: Requires an additional variable to store the array length, which can lead to more memory usage.

2.  **For-each Loop (forEach)**: This approach uses a callback function and does not require storing the array length in a variable.
    *   Pros: More concise and easier to read code. Does not require storing the array length in a variable.
    *   Cons: May lead to performance issues if the callback function is complex or performs multiple operations.

3.  **Some Method**: This approach uses the `some` method, which can stop iterating as soon as it finds an element that matches the condition.
    *   Pros: Can be more efficient than other approaches since it stops iterating early.
    *   Cons: May lead to performance issues if the array is very large.

4.  **For-each Loop (for-of)**: This approach is similar to the previous one but uses the "for...of" keyword instead of a callback function.
    *   Pros: More concise and easier to read code compared to using a callback function with for-each loop.
    *   Cons: May lead to performance issues if the array size is very large.

**Library Usage**

None of the provided JSON defines any external libraries. However, JavaScript's built-in methods and keywords (such as `forEach`, `some`, and "for...of") are used in each test case.

**Special JS Feature or Syntax**

The only special feature used in this benchmark is the use of the "for...of" keyword with an array iteration, which was introduced in ECMAScript 2015. This allows a more concise way to iterate over arrays using the `foreach` expression instead of creating an iterator object.

**Other Alternatives**

Other alternatives for loop constructs in JavaScript include:

1.  **While Loop**: A traditional while loop can be used to achieve similar results.
2.  **Do-While Loop**: Similar to a while loop, but executes the body at least once before checking the condition.
3.  **Using Array.prototype.reduce() and other methods**: Depending on the specific task, reducing an array or using other methods like `every()` or `filter()` might be more efficient or suitable.

These alternatives can often provide different trade-offs in terms of readability, conciseness, performance, or handling edge cases.

for w/length constant vs foreach vs some vs for..of (2) (version: 0) Benchmark.js

Compare loop performance

Comparing performance of: `for (lenght 另外儲存) vs foreach with operation vs some vs for..of vs for (lenght 不另外儲存)`

Created: 2 years ago by: Guest

Go to the latest result

for (lenght 另外儲存)

foreach with operation

some

for..of

for (lenght 不另外儲存)

Historical Performance Data aggregated from 8 community runs

Desktop Results:

Chrome 8 runs

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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

for w/length constant vs foreach vs some vs for..of (2) (version: 0) Benchmark.js

Compare loop performance

Comparing performance of: for (lenght 另外儲存) vs foreach with operation vs some vs for..of vs for (lenght 不另外儲存)

Created: 2 years ago by: Guest

Go to the latest result

for (lenght 另外儲存)

foreach with operation

some

for..of

for (lenght 不另外儲存)

Historical Performance Data aggregated from 8 community runs

Desktop Results:

Chrome 8 runs

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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

Related benchmarks

Comparing performance of: `for (lenght 另外儲存) vs foreach with operation vs some vs for..of vs for (lenght 不另外儲存)`