Benchmark: ...rest vs forEach

Tests:

rest
var arr1 = new Array(100).fill(999); var obj1 = arr1.reduce((acc, n, index) => { acc[index] = index; return acc; }, {}); var data = { 0: '0', 5: '5', 55: '55', 77: '77', 98: '98' }; for(var i = 0; i < 10000; i++) { var res = {...obj1, ...data}; console.log(res); }
forEach
var arr1 = new Array(100).fill(999); var obj1 = arr1.reduce((acc, n, index) => { acc[index] = index; return acc; }, {}); var data = { 0: '0', 5: '5', 55: '55', 77: '77', 98: '98' }; for(var i = 0; i < 10000; i++) { var res = Object.assign({}, obj1); Object.keys(data).forEach(key => { res[key] = data[key]; }); console.log(res); }
for
var arr1 = new Array(100).fill(999); var obj1 = arr1.reduce((acc, n, index) => { acc[index] = index; return acc; }, {}); var data = { 0: '0', 5: '5', 55: '55', 77: '77', 98: '98' }; for(var i = 0; i < 10000; i++) { var res = Object.assign({}, obj1); var keys = Object.keys(data); for(var j = 0; j < keys.length -1; j++) { res[keys[j]] = data[keys[j]]; } console.log(res); }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
rest
forEach
for

Fastest: N/A

Slowest: N/A

Latest run results:

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Autogenerated LLM Summary (model llama3.2:3b, generated one year ago):

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Let's dive into the world of JavaScript microbenchmarks on MeasureThat.net.

**Benchmark Definition**

The benchmark is defined by two options: `rest` and `forEach`, which are used to compare the performance of object assignment in different ways.

**Options Compared**

1. **Rest Spread Operator (`...obj1, ...data`)**: This option uses the rest spread operator to create a new object by spreading the properties of `obj1` and merging them with the properties of `data`.
2. **`forEach()` Method**: This option uses the `forEach()` method to iterate over the keys of `data` and assign their corresponding values to a new object.
3. **Manual Loop (`for`)**: This option uses a traditional loop to manually iterate over the keys of `data` and assign their corresponding values to a new object.

**Pros and Cons**

* **Rest Spread Operator**:
	+ Pros: concise, efficient, and modern syntax.
	+ Cons: may be less readable for those not familiar with it, and can lead to unexpected behavior if not used carefully.
* **`forEach()` Method**:
	+ Pros: easy to read and understand, and is a standard method in JavaScript.
	+ Cons: may be slower than the rest spread operator due to the overhead of calling the `forEach()` method.
* **Manual Loop**:
	+ Pros: straightforward, easy to optimize, and can be faster for large datasets.
	+ Cons: more verbose and prone to errors.

**Library Used**

None is explicitly mentioned in the benchmark definition. However, it's worth noting that the `Object.keys()` method is used to get an array of the object's keys, which is a standard method in JavaScript.

**Special JS Features/Syntax**

The rest spread operator (`...`) and template literals (e.g., `${data[key]}`) are used in the benchmark. These features are modern syntax in JavaScript, introduced in ECMAScript 2015 (ES6).

**Other Alternatives**

If you're interested in exploring other ways to assign object properties, here are some alternatives:

1. **Loops**: You can use `for` loops, `while` loops, or even `Array.prototype.map()` to iterate over the keys and assign values.
2. **Object.assign() with multiple objects**: Instead of using the rest spread operator, you can pass multiple objects to `Object.assign()` to merge their properties.
3. **Using a library like Lodash**: If you need more complex object manipulation, libraries like Lodash provide functions like `merge()` and `assignIn()` that can simplify your code.

Keep in mind that each approach has its trade-offs in terms of performance, readability, and maintainability.

Related benchmarks:

...rest vs forEach (version: 0)

Comparing performance of: rest vs forEach vs for

Created: 5 years ago by: Guest

Jump to the latest result

rest

forEach

for

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

No previous run results

Autogenerated LLM Summary (model llama3.2:3b, generated one year ago):