Benchmark: Array to Key-value object 2

Script Preparation code:

var parsedObject = {};
var test = Array.from({length: 50}).map(x => ({ 
    seconds: 300, 
    icon: 'icon', 
    mcpId: ~~(Math.random()*1000),
    playItem: true,
}));

Tests:

object assing
parsedObject = Object.assign({}, ...test.map(item => ({ [item.mcpId]: item }))) console.log(parsedObject)
for loop
for (let i = 0, len = test.length; i < len; i += 1) { const item = test[i]; const mcpId = item.mcpId; parsedObject[mcpId] = item; } console.log(parsedObject)
reduce
var parsedObject = test.reduce(function(o, val) { o[val.mcpId] = val; return o; }, {}); console.log(parsedObject)

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
object assing
for loop
reduce

Fastest: N/A

Slowest: N/A

Latest run results:

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

LLMs can make mistakes. Check important info.

**What is being tested?**

On the provided JSON, MeasureThat.net is testing how JavaScript engines execute three different approaches to convert an array of objects into key-value objects.

1. **Object.assign()**: This method creates a new object with the specified properties. The `...` syntax before the map function is called spread operator, which takes the values of each inner object in the array and adds them as separate key-value pairs to the new object.
2. **For loop**: A traditional for loop iterates over the array elements and assigns each element to a variable. It then uses that variable's properties (in this case, `mcpId`) to create key-value pairs in a new object.
3. **Reduce()**: The `reduce()` method applies a user-supplied function against an accumulator and each element in the array (from left to right) to reduce it to a single value or output.

**Options compared**

These three approaches are being compared to measure their performance, which may vary depending on the specific JavaScript engine implementation and hardware configuration.

**Pros and Cons of different approaches:**

1. **Object.assign()**:
	* Pros: concise, easy to read, works well for small arrays.
	* Cons: can be slow for large arrays due to creating a new object, potential memory issues if dealing with very large datasets.
2. **For loop**:
	* Pros: straightforward, easy to understand, flexible.
	* Cons: may have performance overhead due to explicit loop iteration and variable assignments.
3. **Reduce()**:
	* Pros: concise, efficient for large arrays, can be optimized by the JavaScript engine.
	* Cons: may require more memory due to creating a temporary accumulator object.

**Library usage**

None of the provided benchmark definitions explicitly use any external libraries or frameworks. However, `Array.prototype.map()` and `Array.prototype.reduce()` are built-in methods on the Array prototype.

**Special JS features or syntax**

No special JavaScript features or syntax are mentioned in the benchmark definitions.

**Other considerations**

When comparing these approaches, it's essential to consider factors like:

* Array size: larger arrays may favor more efficient approaches like reduce().
* Engine optimization: modern JavaScript engines often provide optimizations for built-in methods like reduce().
* Memory usage: large datasets may require more memory for objects or arrays, affecting performance.

**Alternatives**

If you want to explore other alternatives, consider the following:

1. **Destructuring assignment**: Similar to Object.assign(), but uses destructuring syntax to extract properties from objects.
2. **JSON parsing and building**: Using `JSON.parse()` and `JSON.stringify()` can be an alternative for creating key-value pairs.
3. **Iterators or generators**: These can provide a more efficient way to iterate over arrays, especially when combined with reduce().

Keep in mind that these alternatives may not be as concise or readable as the original approaches, but they might offer performance benefits or different use cases.

Related benchmarks:

Array to Key-value object 2 (version: 1)

Comparing performance of: object assing vs for loop vs reduce

Created: 5 years ago by: Registered User

Jump to the latest result

object assing

for loop

reduce

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):