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empty an array in JavaScript - splice vs setting length. 444
(version: 0)
Based on question on http://stackoverflow.com/questions/1232040/how-do-i-empty-an-array-in-javascript
Comparing performance of:
Set length to zero vs Splice
Created:
3 years ago
by:
Guest
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Tests:
Set length to zero
var size = 10000; var arr2 = []; for (var i = 0; i < size; i++){ arr2.push(i); } arr2.length = 64;
Splice
var size = 10000; var arr3 = []; for (var i = 0; i < size; i++){ arr3.push(i); } arr3.splice(64);
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Suite status:
<idle, ready to run>
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Result
Set length to zero
Splice
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N/A
Slowest:
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Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
Let's dive into the world of JavaScript microbenchmarks. **Benchmark Overview** The provided benchmark tests two approaches to empty an array in JavaScript: setting the length to zero and using the `splice` method with a negative index. **Options Compared** There are two main options being compared: 1. **Setting the length to zero**: This approach directly sets the `length` property of the array to zero, effectively clearing its contents. 2. **Using `splice` with a negative index**: This approach uses the `splice` method with an index less than zero (in this case, -64) to remove elements from the end of the array. **Pros and Cons** ### Setting Length to Zero Pros: * Fast and efficient, as it directly modifies the array's internal state. * Simple and easy to understand. Cons: * May not be supported in older browsers or with certain array implementations (e.g., WebAssembly arrays). * May have unintended side effects if used outside of an emptying operation. ### Using `splice` with a Negative Index Pros: * Widely supported across different browsers and array implementations. * Can be useful when working with arrays that need to be truncated in a specific way. Cons: * Slower than setting the length to zero, as it involves a more complex algorithm to find and remove elements from the end of the array. * Requires careful handling to avoid errors or unexpected behavior. **Library/Feature Considerations** Neither of these approaches relies on any specific libraries or advanced JavaScript features. However, some browsers may optimize or modify the execution behavior in certain situations (e.g., Safari's array optimization). **Other Alternatives** Besides setting the length to zero and using `splice` with a negative index, other methods for emptying arrays include: * Using the `fill` method with an argument of zero: `arr.fill(0)` * Creating a new array with the same length but no elements: `new Array(size).fill().map((_, i) => null)` (a more complex approach) * Using a library like Lodash's `empty` function It's worth noting that some browsers may have additional methods or optimizations for emptying arrays, such as `arr.set(0, 0)` on Safari. In summary, setting the length to zero is generally the fastest and most straightforward way to empty an array in JavaScript, but using `splice` with a negative index can be useful when working with certain array implementations or requirements.
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