Benchmark: Creating objects

Script Preparation code:

setC = v => o => ({
  a: o.a,
  b: o.b,
  c: v,
  d: o.d,
  e: o.e,
  f: o.f,
  g: o.g,
  h: o.h,
  i: o.i,
  j: o.j
})

o = {
  a: 1,
  b: 2,
  c: 3,
  d: 4,
  e: 5,
  f: 6,
  g: 7,
  h: 8,
  i: 9,
  j: 0
};

Tests:

Assign
assign = Object.assign({}, o, {c: 4});
Spread
spread = {...o, c: 4};
Literal
literal = setC(4)(o)

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Assign
Spread
Literal

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.

Let's break down the provided benchmarking test cases and explain what is being tested, compared, and the pros and cons of each approach.

**Benchmark Overview**

The benchmark measures the performance of three different approaches to create objects with additional properties:

1. Assign (using `Object.assign`)
2. Spread (using the spread operator)
3. Literal (using a custom function `setC`)

Each test case uses the same input object `o` and creates a new object with an additional property `c`.

**Test Case 1: Assign**

The benchmark definition is:
```javascript
assign = Object.assign({}, o, { c: 4 });
```
This approach uses the `Object.assign` method to create a new object by copying properties from `o` and adding a new property `c` with value `4`.

**Pros:** Simple and efficient way to add properties to an object.

**Cons:** Can lead to slower performance if `o` is large, as it creates a new copy of the entire object.

**Test Case 2: Spread**

The benchmark definition is:
```javascript
spread = {...o, c: 4};
```
This approach uses the spread operator (`...`) to create a new object by copying properties from `o` and adding a new property `c` with value `4`.

**Pros:** Fast and efficient way to add properties to an object, especially when compared to `Object.assign`. Also, it creates a shallow copy of the original object.

**Cons:** May not work correctly if `o` contains nested objects or functions, as only shallow copying is performed.

**Test Case 3: Literal**

The benchmark definition is:
```javascript
literal = setC(4)(o);
```
This approach uses a custom function `setC` to create a new object with additional properties. The `setC` function takes two arguments: the value of the new property (`4`) and the original object `o`.

**Pros:** Fast and efficient way to add properties to an object, especially when compared to `Object.assign`. Also, it creates a shallow copy of the original object.

**Cons:** Requires defining a custom function `setC`, which can add complexity to the codebase.

**Library:**

The benchmark uses the `Object` global object, which is part of the JavaScript standard library. The `Object.assign` and spread operator are also part of the standard library.

**Special JS Feature/Syntax:**

There are no special JavaScript features or syntax used in this benchmark. However, it's worth noting that the use of arrow functions (`=>`) in the `setC` function is a modern JavaScript feature introduced in ECMAScript 2015 (ES6).

**Other Alternatives:**

Other approaches to create objects with additional properties could include:

* Using the `concat()` method to merge two arrays/object
* Using a library like Lodash to provide a more robust way of merging objects
* Using a template literal to create an object from a string

However, these alternatives are not tested in this benchmark, and their performance would likely be different compared to the approaches used here.

Related benchmarks:

Creating objects (version: 0)

Comparing performance of: Assign vs Spread vs Literal

Created: 7 years ago by: Guest

Jump to the latest result

Assign

Spread

Literal

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):