Benchmark: for in break vs object keys better

Script Preparation code:

var testObj = {}
for (let i = 0; i < 10000; i++) {
  const randomString = Math.random().toString(36).substr(2, 5);
  testObj[randomString] = randomString;
}

Tests:

for in break
let output; for (const key in testObj) { output = testObj[key]; break; } console.log(output);
Object keys
let output; output = Object.values(testObj)[0]; console.log(output);
Object keys for real
let output; output = testObj[Object.keys[0]]; console.log(output);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
for in break
Object keys
Object keys for real

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 benchmark and explain what's being tested, compared options, pros and cons of each approach, and other considerations.

**Benchmark Purpose**

The purpose of this benchmark is to compare the performance of three different ways to access object properties in JavaScript:

1. `for...in` loop with a `break` statement
2. Using `Object.values()` to get an array of property values
3. Directly accessing the first property using its key (`testObj[0]`)

**Options Compared**

The benchmark is comparing three different approaches to achieve a similar goal:

* **Approach 1: `for...in` loop with a `break` statement**: This method iterates over the object's properties, breaks out of the loop when the desired property is found, and then logs its value.
* **Approach 2: Using `Object.values()`**: This method uses the `Object.values()` method to get an array of all property values in the object. The first value in this array is logged as output.
* **Approach 3: Directly accessing the first property using its key (`testObj[0]`)**: This method directly accesses the first property by its key, which is assumed to be the desired output.

**Pros and Cons of Each Approach**

1. **`for...in` loop with a `break` statement**:
	* Pros: Can be more readable and easier to understand for complex objects.
	* Cons: May not be as efficient since it iterates over all properties before breaking out.
2. **Using `Object.values()`**:
	* Pros: More concise and arguably easier to read.
	* Cons: May require more memory since it creates an array of property values.
3. **Directly accessing the first property using its key (`testObj[0]`)**:
	* Pros: Fastest since it directly accesses a specific property without iterating.
	* Cons: Less readable and may not work if the object has no properties or if the desired property is not found.

**Library Used**

None. This benchmark does not use any external libraries.

**Special JS Feature/Syntax**

The benchmark uses `Object.values()` which is a feature introduced in ECMAScript 2019 (ES2020). It's a way to get an array of all property values in an object without using the bracket notation (`obj[key]`).

**Device/OS Considerations**

The benchmark results show that Chrome 86 running on Windows Desktop has the highest `ExecutionsPerSecond` value, indicating faster performance. The exact reasons for this difference are not specified.

**Alternatives**

Other alternatives to achieve similar goals could include:

* Using a `for...of` loop with an iterator or a custom function to iterate over object properties.
* Using `Object.keys()` and then accessing the first property using bracket notation (`testObj[Object.keys(testObj)[0]]`).
* Using a library like Lodash, which provides utility functions for working with objects.

In summary, this benchmark compares three approaches to access object properties in JavaScript: `for...in` loop with a `break` statement, `Object.values()`, and direct property access using its key. Each approach has pros and cons, and the results show that the fastest method depends on the specific use case.

Related benchmarks:

for in break vs object keys better (version: 0)

Comparing performance of: for in break vs Object keys vs Object keys for real

Created: 5 years ago by: Guest

Jump to the latest result

for in break

Object keys

Object keys for real

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):