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maintain a fixed list length
(version: 0)
Comparing performance of:
slice vs splice vs shift vs indexed
Created:
4 years ago
by:
Guest
Jump to the latest result
Script Preparation code:
var list = []; for (var i = 0; i < 1000 * 1000; i++) { list.push(i); } idx = 0;
Tests:
slice
list.push('slice'); list = list.slice(1);
splice
list.push('splice'); list.splice(0, 1);
shift
list.push('splice'); list.shift();
indexed
list[idx] = 'splice'; idx = (idx++) % list.length; // Needs some formatting when you actually need to use the list
Rendered benchmark preparation results:
Suite status:
<idle, ready to run>
Run tests (4)
Previous results
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Test case name
Result
slice
splice
shift
indexed
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 definition and test cases to understand what is being tested. **Benchmark Definition** The benchmark definition is a JSON object that describes how to create a microbenchmark. In this case, it consists of three parts: 1. **Script Preparation Code**: This code initializes an empty array `list` with 1 million elements using a `for` loop. The variable `idx` is also initialized. 2. **Html Preparation Code**: This field is empty, which means no HTML-specific code needs to be executed before running the benchmark. 3. **Benchmark Script**: This is where the actual benchmarking happens. The script performs three different operations on the `list` array: * `splice`: Removes the first element from the list using `splice`. * `shift`: Removes the first element from the list using `shift`. * `slice`: Creates a new slice of the list, excluding the first element, and assigns it back to the original list. **Test Cases** The test cases are individual JavaScript code snippets that perform these operations on the `list` array. Each test case has a unique name (e.g., "splice", "shift", etc.). Here's what each operation does: * **Splice**: Removes the first element from the list using `splice(0, 1)`. * **Shift**: Removes and returns the first element from the list using `shift()`. * **Slice**: Creates a new slice of the list, excluding the first element (index 0), and assigns it back to the original list. **Library Used** None of the provided test cases use any external libraries. The benchmarking script only relies on built-in JavaScript methods. **Special JS Features or Syntax** The `slice` method uses a new operator (`new`) in its implementation, which is not explicitly mentioned in the benchmark definition. This is because some browsers may have different implementations for this method. **Pros and Cons of Different Approaches** Each operation has its pros and cons: * **Splice**: Pros: efficient removal of elements; Cons: modifies the original list. * **Shift**: Pros: simple and efficient removal of elements; Cons: returns the removed element, which may not be desirable. * **Slice**: Pros: creates a new slice without modifying the original list; Cons: potentially slower than other methods due to its overhead. **Alternative Approaches** Some alternative approaches could have been used: * Instead of using `splice`, you could use `array.filter()` or `array.map()` to create a new array with the same elements, excluding the first one. * For removing the first element, you could use `array.pop()` or `array.splice(1, 0)` (which is less common). * Using `slice` as a method call instead of the new operator (`new slice()`) might be more browser-friendly. Keep in mind that these alternatives may have different performance characteristics and trade-offs compared to the original implementation.
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