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(version: 0)
Comparing performance of:
spread vs assign
Created:
3 years ago
by:
Guest
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Tests:
spread
let cookies = Math.random() > 0.5 ? "" : "sjdhfkj"; let headers = { test: "made", ...(cookies && { Cookie: cookies }) };
assign
let cookies = Math.random() > 0.5 ? "" : "sjdhfkj"; let headers = Object.assign({ test: "made"}, cookies ? { Cookie: cookies } : {});
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Suite status:
<idle, ready to run>
Run tests (2)
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Test case name
Result
spread
assign
Fastest:
N/A
Slowest:
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Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
I'd be happy to help explain the benchmark and its results. **What is being tested?** The provided JSON represents two test cases for measuring the performance difference between using the spread operator (`...`) and the `Object.assign()` method in JavaScript. In the first test case, "spread", a variable `cookies` is assigned a random value (either an empty string or a string with some characters). This value is then used to create an object `headers` by spreading the `cookies` object into it. The resulting `headers` object has a `Cookie` property only if `cookies` is truthy. In the second test case, "assign", the same logic applies, but instead of using the spread operator, the `Object.assign()` method is used to merge the `cookies` object into the initial object `{ test: 'made' }`. **Options compared** The two options being compared are: 1. **Spread Operator (`...`)**: This syntax allows you to create a new object by copying all own enumerable properties from an existing object. 2. **Object.assign() method**: This method creates a new object and copies all own enumerable properties from the given objects. **Pros and Cons** * Spread Operator: + Pros: concise, readable, and efficient way to create new objects. + Cons: may be slower than `Object.assign()` for very large objects due to the creation of intermediate arrays. * Object.assign() method: + Pros: widely supported, can handle large objects efficiently by avoiding unnecessary array creations. + Cons: more verbose than the spread operator. **Library and purpose** There is no specific library mentioned in the provided JSON. However, it's worth noting that some browsers may have their own optimizations or implementations for `Object.assign()` that could affect performance. **Special JS feature or syntax** The only special feature used here is the use of template literals (e.g., `\r\n`) to create multiline strings. This feature allows you to embed expressions inside string literals, which can make code more readable and concise. However, it's not a deeply complex feature that would require explanation. **Other alternatives** If performance comparisons were being made for other aspects of JavaScript, some alternative approaches might include: * Using `Object.create()` instead of `Object.assign()` * Comparing the performance of different object literal syntaxes (e.g., `{ foo: 'bar' }` vs. `[foo: 'bar']`) * Measuring the performance of different methods for iterating over objects (e.g., `for...in` vs. `forEach()`) Keep in mind that these alternatives would depend on the specific use case and requirements being measured. Overall, the provided benchmark is a simple yet meaningful test case that highlights the trade-offs between using the spread operator and the `Object.assign()` method in JavaScript.
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