Benchmark: Object spread vs Object assign

Script Preparation code:

var first = {
  foo: "string",
  bar: 42,
  baz: 100.56,
  quux: "another string",
  foobar: {
    one: "foo bar",
    two: "bar foo"
  },
  bazbaz: function (a, b) {
    return a * a % b + 100 / b;
  }
};

var second = {
  one: "x",
  two: "y",
  three: "z",
  x: "one",
  y: "two",
  z: "three",
  foo: "string 2",
  bar: 43
};

Tests:

Object assign
const third_assign = Object.assign({}, first, second); return third_assign;
Object spread
const third_spread = { ...first, ...second, }; return third_spread;

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Object assign
Object spread

Fastest: N/A

Slowest: N/A

Latest run results:

No previous run results

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

LLMs can make mistakes. Check important info.

**Benchmark Overview**

MeasureThat.net is a website that allows users to create and run JavaScript microbenchmarks, comparing different approaches to achieve the same goal. In this case, we have two test cases: "Object assign" and "Object spread". The benchmark measures which approach is faster, using a specific dataset provided in the Benchmark Definition JSON.

**Benchmark Definition JSON**

The Benchmark Definition JSON contains information about the script preparation code, which defines an object `first` with various properties, including nested objects and functions. This object will be used to test two different approaches: object assignment (`Object.assign`) and object spread (`...`).

The Script Preparation Code is:
```javascript
var first = {
  foo: "string",
  bar: 42,
  baz: 100.56,
  quux: "another string",
  foobar: {
    one: "foo bar",
    two: "bar foo"
  },
  bazbaz: function (a, b) {
    return a * a % b + 100 / b;
  }
};

var second = {
  one: "x",
  two: "y",
  three: "z",
  x: "one",
  y: "two",
  z: "three",
  foo: "string 2",
  bar: 43
};
```
**Options Compared**

Two options are compared:

1. **Object assignment (`Object.assign`)**: This approach uses the `Object.assign()` method to merge two objects into a new object.
```javascript
const third_assign = Object.assign({}, first, second);
return third_assign;
```
2. **Object spread (`...`)**: This approach uses the spread operator (`...`) to create a new object with properties from both `first` and `second`.
```javascript
const third_spread = {
  ...first,
  ...second,
};
return third_spread;
```
**Pros and Cons**

**Object assignment (`Object.assign`)**

Pros:

* More explicit and readable code
* Works well for merging objects with simple property names

Cons:

* Can be slower due to the overhead of function calls
* May not work as expected if properties have different types (e.g., numbers vs strings)

**Object spread (`...`)**

Pros:

* Faster and more concise code
* Works well for merging objects with simple property names
* Supports nested objects and arrays

Cons:

* Less explicit and readable code (may require additional configuration)
* May not work as expected if properties have different types (e.g., numbers vs strings)

**Library and Special JS Feature**

There is no specific library used in this benchmark, but it does use the spread operator (`...`), which is a modern JavaScript feature introduced in ECMAScript 2018.

**Other Considerations**

* **Performance**: The benchmark measures performance by executing each test case multiple times and measuring the execution time.
* **Platform dependence**: The benchmark runs on different devices (Desktop) and browsers (Chrome 84).
* **Test duration**: The benchmark executes each test case for a certain number of executions per second.

**Alternatives**

Other alternatives to these approaches could include:

1. Using a library like Lodash or Ramda, which provides a more functional programming style for merging objects.
2. Using a different data structure, such as an array or a JSON object with custom merge functions.
3. Optimizing the benchmark code using techniques like memoization or caching.

However, these alternatives may not be relevant to this specific benchmark, which focuses on comparing two basic approaches to merging objects: object assignment and object spread.

Related benchmarks:

Object spread vs Object assign (version: 0)

spread vs assign

Comparing performance of: Object assign vs Object spread

Created: 7 years ago by: Guest

Jump to the latest result

Object assign

Object spread

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):