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Array constructor vs literal
(version: 0)
Comparing performance of:
Array constructor - 1000000 items vs Array literal - 1000000 items
Created:
9 years ago
by:
Guest
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Tests:
Array constructor - 1000000 items
var n = 1000000; var arr = new Array(n); for (var i = 0; i < n; i++) { arr[i] = i; }
Array literal - 1000000 items
var n = 1000000; var arr = []; for (var i = 0; i < n; i++) { arr.push(i); }
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Suite status:
<idle, ready to run>
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Test case name
Result
Array constructor - 1000000 items
Array literal - 1000000 items
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N/A
Slowest:
N/A
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Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
I'll explain the JavaScript benchmark you provided. **Benchmark Purpose** The test compares two approaches to create an array in JavaScript: using the `new Array()` constructor and using the literal syntax (i.e., simply assigning an empty array `[]`). **Options Compared** 1. **Array Constructor (`new Array()`)**: This method involves creating a new instance of the `Array` class, passing the desired length as an argument. 2. **Literal Syntax (`[]`)**: This method uses the empty square bracket syntax to create an array. **Pros and Cons** **Array Constructor** * Pros: + Can be faster for large arrays since it avoids the overhead of parsing the literal syntax. + Allows for more control over array properties (e.g., setting length, prototype). * Cons: + More verbose and less concise than the literal syntax. + May involve a higher memory allocation overhead. **Literal Syntax** * Pros: + More concise and easier to read than the array constructor approach. + Less prone to errors since it's a more straightforward syntax. * Cons: + May be slower for large arrays due to parsing overhead. + Less control over array properties (e.g., setting length, prototype). **Other Considerations** Both approaches have their trade-offs. The array constructor approach provides more control but at the cost of conciseness and readability. The literal syntax approach is more concise and easier to read but may be slower for large arrays. **Library/External Functions** None mentioned in this benchmark. **Special JS Features/Syntax** None explicitly mentioned, but note that modern JavaScript supports features like `let` and `const` declarations, which are not used in these test cases. However, the use of `var` instead of `let` or `const` is noted, as it can lead to variable hoisting issues. **Alternatives** Other ways to create arrays in JavaScript include: 1. Using `Array.from()` method, which creates a new array from an iterable (e.g., an array literal). 2. Using `Array()` function with a callback function (e.g., `new Array(n).fill(0)`). Keep in mind that these alternatives may have different performance characteristics compared to the methods tested here. Overall, this benchmark provides a simple and straightforward comparison of two common approaches to creating arrays in JavaScript, allowing users to compare their performance and make informed decisions based on their specific use cases.
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