Benchmark: Object.values vs for in loop vs for loop v3

Tests:

mapForIn
const obj = {}; for (let i = 0; i <= 10000; i++) { obj[i] = { id: i }; }; const mapForIn = () => { const arr = []; for (let key in obj) { if (Object.hasOwnProperty(obj)) { arr.push(obj[key].id); } } return arr; } mapForIn();
mapValues
const obj = {}; for (let i = 0; i <= 10000; i++) { obj[i] = { id: i }; }; const mapValues = () => Object.values(obj).map(v => v.id) mapValues();
for loop
const obj = {}; const keys = []; for (let i = 0; i <= 10000; i++) { obj[i] = { id: i }; keys.push(i); }; const numberOfKeys = keys.length - 1; const mapFor = () => { const arr = []; for (let i = 0; i <= numberOfKeys; i++) { arr[i] = obj[i].id; }; return arr; }; mapFor();

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
mapForIn
mapValues
for loop

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 break down the provided JSON data and explain what each test case is testing, along with their pros and cons.

**Benchmark Definition**

The benchmark definition is not explicitly provided in the JSON data, but based on the individual test cases, we can infer that it's a comparison of three different methods to extract values from an object:

1. `Object.values` (using the `mapValues` function)
2. For loop with `in` operator (using the `for loop` function)
3. For loop without using `in` operator (using the `mapForIn` function)

**Individual Test Cases**

Here's a brief explanation of each test case:

### mapForIn

This test case uses the `Object.hasOwnProperty()` method to iterate over the object properties, which is not a recommended way to do so. Instead, you should use the `in` operator or `for...in` loop.

```javascript
const obj = {};

// ...

mapForIn();
```

The `for...in` loop or `in` operator is a more modern and efficient way to iterate over object properties. This test case likely uses the old approach for comparison purposes.

**Pros:** None
**Cons:**

* Using `Object.hasOwnProperty()` and its unnecessary checks can slow down performance.
* This approach is deprecated and not recommended in modern JavaScript code.

### mapValues

This test case uses the `map` function to apply a transformation to an array of values returned by `Object.values()`. The resulting array is then pushed into another array, which is not necessary. However, this approach still uses `Object.values()` and `map`, making it more efficient than the `for...in` loop or `in` operator.

```javascript
const obj = {};

// ...

const mapValues = () => Object.values(obj).map(v => v.id);

mapValues();
```

**Pros:** More efficient than `for...in` loop, uses modern JavaScript features.
**Cons:** Creates an unnecessary array and pushes elements into it.

### for loop

This test case uses a traditional for loop without using the `in` operator or `for...in` loop. It manually keeps track of the index and loops through the object properties using the original key.

```javascript
const obj = {};

// ...

const numberOfKeys = keys.length - 1;
const mapFor = () => {
  const arr = [];
  for (let i = 0; i <= numberOfKeys; i++) { // off-by-one error
    arr[i] = obj[i].id;
  }
  return arr;
};

mapFor();
```

**Pros:** None notable.
**Cons:**

* Manually keeps track of the index, which can lead to off-by-one errors.
* Does not use modern JavaScript features or object iteration methods.

**Library: None**

There are no libraries used in these test cases.

**Special JS Feature/Syntax:**

None.

**Other Alternatives**

If you want to optimize this benchmark, consider using:

1. `Object.entries()` and `map` instead of `Object.values()`: `Array.from(Object.entries(obj)).map(([key, value]) => value.id);`
2. Modern for loop with an iterator (e.g., `for...of`) or `forEach`: This is already done in the `mapValues` test case.
3. Using a library like Lodash to handle array manipulation: Lodash provides functions like `mapValues`, `forEach`, and others that can simplify this benchmark.

In summary, while each approach has its pros and cons, using modern JavaScript features and iteration methods can make your code more efficient and readable.

Related benchmarks:

Object.values vs for in loop vs for loop v3 (version: 0)

Comparing performance of: mapForIn vs mapValues vs for loop

Created: 3 years ago by: Guest

Jump to the latest result

mapForIn

mapValues

for loop

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):