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for (reverse with length) vs for vs every vs forEach with small array
(version: 0)
Comparing performance of:
for vs for (reverse with length) vs some vs every
Created:
4 years ago
by:
Guest
Jump to the latest result
Script Preparation code:
var array = new Array(100);
Tests:
for
for (var i = 0; i < array.length; i++) { array[i]; }
for (reverse with length)
var length = array.length; for (var i = length; --i >= 0;) { array[i]; }
some
array.some(function(i) { array[i]; });
every
array.every(function(i) { array[i]; });
Rendered benchmark preparation results:
Suite status:
<idle, ready to run>
Run tests (4)
Previous results
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Test case name
Result
for
for (reverse with length)
some
every
Fastest:
N/A
Slowest:
N/A
Latest run results:
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Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
Let's break down the provided benchmark and explain what's being tested, compared, and the pros and cons of each approach. **Benchmark Overview** The benchmark measures the performance of different JavaScript loops on a small array of 100 elements: * `for`: Traditional loop with an incrementing index * `for (reverse with length)`: A reverse iteration using the `length` property and decrementing the index * `some`, `every`: Iteration methods provided by modern JavaScript arrays **Script Preparation Code** The script preparation code initializes a new array of 100 elements: `var array = new Array(100);`. This ensures that all test cases have access to the same data. **Html Preparation Code** There is no html preparation code, which means the benchmark focuses solely on JavaScript performance. **Individual Test Cases** Each test case has its own unique characteristics: * **`for`**: A traditional loop with an incrementing index. The pros of this approach are that it's widely supported and easy to understand. However, it may not be as efficient for large arrays due to the overhead of incrementing the index. * **`for (reverse with length)`**: This reverse iteration uses the `length` property and decrementing the index to access array elements in reverse order. The pros are that it can be more efficient than traditional loops when iterating over arrays in reverse, especially for large datasets. However, it may require additional code and is less widely supported. * **`some`, `every`**: These iteration methods allow you to test array elements against a predicate function without explicit indexing. `some()` returns `true` as soon as an element passes the test, while `every()` returns `true` only if all elements pass. The pros of these methods are that they can simplify code and reduce errors, but may introduce overhead due to the additional function calls. **Benchmark Results** The latest benchmark results show the performance metrics for each test case: * **`every`**: The fastest execution rate (3719067 executions per second) likely due to its optimized implementation. * **`some`**: A slower execution rate (3525439.75 executions per second), possibly because it needs to evaluate multiple elements before returning a result. * **`for (reverse with length)`**: An even slower execution rate (102734.2265625 executions per second) likely due to the additional overhead of reverse iteration and decrementing the index. * **`for`**: The slowest execution rate (53966.0 executions per second), possibly because it's a traditional loop without any optimization. **Library Used** None, as this benchmark focuses solely on native JavaScript features. **Special JS Feature or Syntax** The `some()` and `every()` methods use modern JavaScript array iteration syntax, which is not universally supported across all browsers. However, Chrome 97 (the specific browser used in the benchmark) has good support for these methods. **Other Alternatives** Other iteration methods, such as `forEach()`, are also available but were not tested in this benchmark. In summary, the benchmark compares the performance of different JavaScript loops and array iteration methods on a small array. The results highlight the efficiency of optimized methods like `every()` and the challenges of reverse iteration using `for (reverse with length)`.
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