function generateTestArray() { const result = []; for (let i = 0; i < 1000000; ++i) { result.push({ a: i, b: i / 2, r: 0, }); } return result;}const array = generateTestArray();array.forEach((x) => { x.r = x.a + x.b;});const array = generateTestArray();for(const x of array) { x.r = x.a + x.b;}--enable-precise-memory-info flag.
| Test case name | Result |
|---|---|
| .forEach | |
| for..of |
| Test name | Executions per second |
|---|---|
| .forEach | 15.5 Ops/sec |
| for..of | 22.1 Ops/sec |
Benchmark Overview
The provided benchmark measures the performance of two different approaches for iterating over an array: the traditional .forEach method and the newer for...of loop.
Options Compared
Two options are compared:
.forEach: A traditional method for iterating over an array, where each element is passed to a callback function.for...of: A new syntax introduced in ECMAScript 2015 (ES6) for iterating over arrays and other iterable objects.Pros and Cons
.forEach:for...of:.forEach.Library Usage
None of the benchmark tests use a specific library. The test cases only involve built-in JavaScript features.
Special JS Features/Syntax
The for...of loop is a special feature introduced in ES6 (ECMAScript 2015) for iterating over arrays and other iterable objects. It provides a more concise way to iterate over collections of values without the need for explicit indexing or callbacks.
Other Alternatives
If you're interested in exploring other alternatives, here are a few:
.map(): While not designed specifically for iteration, .map() can be used to transform arrays by applying a callback function to each element.reduce(): Another built-in JavaScript method that can be used for iterating over arrays, but it's primarily used for reducing the array to a single value.Benchmark Considerations
When creating benchmarks like this one, consider the following:
By considering these factors, you can create a robust and informative benchmark that helps identify performance differences between different JavaScript iteration methods.
