Benchmark: Tab length - MeasureThat.net

HTML Preparation code:

<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.4.2/angular.min.js"></script>

Script Preparation code:

var tab = [];
tab[999]= null;
var i = 0;
var sum = 0;

Tests:

test 1
for(i=0; i<tab.length;i++){sum += 1;}
test 2
var a = tab.length; for(i=0; i<a;i++){sum += 1;}
test 3
_.forEach(tab, function(){sum += 1;});
test 4
angular.forEach(tab, function() {sum += 1;});
test 5
tab.every(function (x) {sum += 1});

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
test 1
test 2
test 3
test 4
test 5

Fastest: N/A

Slowest: N/A

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Autogenerated LLM Summary (model gemma2:9b, generated one year ago):

LLMs can make mistakes. Check important info.

This benchmark measures the performance of different ways to iterate over a large array in JavaScript.  Let's break down the test cases and their implications:

**The Setup:**

* **Array Initialization:** The provided JSON sets up an array named `tab`. This array has 1000 elements, but only the last one (`tab[999]`) is initialized with a value (set to `null`).  
* **`sum` Variable:** A variable named `sum` is created and initialized to 0. It will be used to accumulate the result of iterating over the array.

**The Tests:**

1. **`test 1`: Traditional for loop:** This test uses a standard `for` loop to iterate from index 0 up to the length of the `tab` array.  For each element, it increments the `sum` variable by 1.
   * **Pros:** Simple, intuitive, often performant for basic iteration.
   * **Cons:** Can be less flexible than other methods for complex operations within the loop.

2. **`test 2`:  Loop with pre-calculated length:** This test calculates the length of the array (`a = tab.length`) before the loop. It then iterates using this pre-calculated value.
   * **Pros:** Might be slightly faster than `test 1` in some cases due to avoiding repeated calls to `tab.length` inside the loop.
   * **Cons:** Doesn't always offer significant performance gains, and introduces a minor extra variable.

3. **`test 3`: Underscore.js `forEach`:** This test utilizes the `_.forEach` function from the Underscore.js library. It iterates over each element in the array and executes a provided callback function (which increments `sum`).
   * **Pros:** Concise, readable syntax. Offers convenience methods for common array operations.
   * **Cons:** Requires an external library. Might introduce overhead depending on the specific use case.

4. **`test 4`: AngularJS `forEach`:**  This test uses the `angular.forEach` function from the AngularJS framework. It works similarly to Underscore.js's `forEach`.
   * **Pros:** Concise, readable syntax (if you're familiar with AngularJS). Offers convenience methods for common array operations within its framework.
   * **Cons:** Requires a specific framework dependency. Might not be necessary or appropriate outside of AngularJS projects.

5. **`test 5`: Underscore.js `every`:** This test employs the `_.every` function from Underscore.js. It iterates through each element in the array and returns true if all elements pass a condition (in this case, it always increments `sum`).
   * **Pros:** Can be useful for checking conditions across arrays efficiently. 
   * **Cons:** Not the most direct way to simply sum array elements; can introduce unnecessary overhead if your goal is purely summation.

**Alternatives:**

*  **Array `reduce` method:** This built-in JavaScript method provides a concise and efficient way to iterate over an array and accumulate a single result (which in this case would be the sum).

Let me know if you have any other questions or want to explore specific aspects of these tests in more detail!

Related benchmarks:

Tab length (version: 0)

Comparing performance of: test 1 vs test 2 vs test 3 vs test 4 vs test 5

Created: 8 years ago by: Guest

Jump to the latest result

test 1

test 2

test 3

test 4

test 5

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

No previous run results

Autogenerated LLM Summary (model gemma2:9b, generated one year ago):