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Foreach vs Spread
(version: 0)
Comparing performance of:
Foreach vs Spread
Created:
6 years ago
by:
Guest
Go to the latest result
Tests:
Foreach
var a = new Map(); a.set("a", 12345); a.set("b", 45678); a.set("c", 13579); a.set("d", 24680); a.set("e", 09876); a.set("f", 54321); a.set("g", 12121); a.set("h", 23232); a.set("i", 45454); var b = []; a.forEach((c) => b.push(c));
Spread
var a = new Map(); a.set("a", 12345); a.set("b", 45678); a.set("c", 13579); a.set("d", 24680); a.set("e", 09876); a.set("f", 54321); a.set("g", 12121); a.set("h", 23232); a.set("i", 45454); var b = []; b = [...b, ...a ];
Rendered benchmark preparation results:
Suite status:
<idle, ready to run>
Run tests (2)
Previous results
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Test case name
Result
Foreach
Spread
Fastest:
N/A
Slowest:
N/A
Latest run results:
Run details:
(Test run date:
one year ago
)
User agent:
Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/131.0.0.0 Safari/537.36
Browser/OS:
Chrome 131 on Mac OS X 10.15.7
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Embed Benchmark Result
<iframe src="https://measurethat.net/Embed?id=576716" width="100%" height="500px"></iframe>
Spread
4.7M/s
Foreach
4.2M/s
View exact numbers
Test name
Executions per second
✓
Spread
4,733,764 Ops/sec
Foreach
4,238,518 Ops/sec
Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
Let's dive into the benchmark. **What is being tested?** The provided benchmark measures the performance of two approaches when iterating over an array of objects using `Map` and `Array`. In the first approach, "Foreach", the code uses the `forEach()` method to iterate over the keys of the `Map` object, and pushes each key into an array (`b`). This is done in a specific order: `a.forEach((c) => b.push(c));` In the second approach, "Spread", the code uses the spread operator (`...`) to create a new array that includes all elements from another array (`b`) and then spreads its own elements (keys of the `Map` object `a`). This is done as follows: `var b = []; b = [...b, ...a];` **Options being compared** Two options are being compared: 1. **Foreach**: Using `forEach()` method to iterate over the keys of a `Map` object. 2. **Spread**: Using the spread operator (`...`) to create a new array that includes all elements from another array and then spreads its own elements. **Pros and Cons of each approach** * **Foreach Approach:** * Pros: * Easy to read and understand, as it iterates over the keys in a straightforward manner. * Can be used when you need to perform an operation on each key in the `Map`. * Cons: * May incur additional overhead due to the call stack management of the `forEach()` method. * **Spread Approach:** * Pros: * More concise and potentially faster, as it avoids the overhead of the `forEach()` method and creates a new array all at once. * Can be used when you need to perform an operation on each element in the original array (`a`). * Cons: * Less readable than the foreach approach, as the spread operator is not immediately intuitive for iterating over objects. **Other Considerations** * The benchmark assumes that the `Map` object's keys are not too large or complex to be pushed into an array. If you need to handle larger values, you may want to consider using a more optimized data structure. * The performance difference between these two approaches can depend on various factors such as JavaScript engine optimizations, array and map sizes, and device configurations. **Library used** The `Map` object is a built-in JavaScript object that stores key-value pairs. Its primary purpose is to provide an efficient way of storing and retrieving data by using keys for lookup. **Special JS feature or syntax** This benchmark uses the spread operator (`...`), which was introduced in ECMAScript 2015 (ES6). The spread operator allows you to expand array or object elements into a new array or object. In this benchmark, it's used to create a new array that includes all elements from `b` and then spreads its own elements. **Alternatives** If you're looking for alternatives to these approaches, here are a few: * For iterating over an array of objects when performance is critical: * Using a `for...in` loop instead of `forEach()`, as it avoids the overhead of the call stack management. * For creating a new array from an existing one with additional elements: * Using other methods like `concat()`, `push()` along with some creative use of spread operator or even manual iteration. Overall, this benchmark provides valuable insights into how different approaches can impact performance when working with `Map` objects and arrays in JavaScript.
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