Benchmark: for-in vs Object.keys.forEach vs Object.keys with for loop vs Object.entries

Script Preparation code:

var obj = {
    'a': 1,
    'b': 2,
    'c': 3,
    'd': 4,
    'e': 5,
    'f': 6,
    'g': 7
};

Tests:

for-in
for (var i = 10000; i > 0; i--) { for (var key in obj) { if (obj.hasOwnProperty(key)) { console.log(obj[key]); } } }
Object.keys.forEach
for (var i=10000; i > 0; i--) { Object.keys(obj).forEach(key => console.log(obj[key])); }
Object.keys with for of loop
for (var i=10000; i > 0; i--) { for (var key of Object.keys(obj)) { console.log(obj[key]); } }
Object.entries
for (var i=10000; i > 0; i--) { for (const [key, value] of Object.entries(obj)) { console.log(value); } }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
for-in
Object.keys.forEach
Object.keys with for of loop
Object.entries

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 benchmark and explain what's being tested.

**Benchmark Overview**

The benchmark measures the performance of different approaches to iterate over an object's properties in JavaScript. The test cases compare:

1. `for-in` loop
2. Using `Object.keys()` with a `forEach()` method
3. Using `Object.keys()` with a traditional `for` loop
4. Using `Object.entries()` with a `for...of` loop

**Options Comparison**

Here's a brief overview of each option:

1. **For-in loop**: This is an older way to iterate over an object's properties, using the `in` operator and the `hasOwnProperty()` method to check if a property belongs to the object. While still supported, this approach has been largely replaced by more modern methods.
2. **Object.keys().forEach()**: This uses the `Object.keys()` method to get an array of the object's property names, and then iterates over that array using the `forEach()` method. This is a more modern way to iterate over objects, but may incur additional overhead due to the method call.
3. **Object.keys().for...of loop**: Similar to the previous option, but uses a traditional `for` loop with the `Object.keys()` method as its source of truth. This approach avoids the overhead of the `forEach()` method and is more concise.
4. **Object.entries().for...of loop**: This uses the `Object.entries()` method to get an array of key-value pairs, and then iterates over that array using a `for...of` loop. While not as straightforward as other options, this approach provides direct access to both keys and values.

**Pros and Cons**

Here are some pros and cons for each option:

1. **For-in loop**:
	* Pros: Simple, widely supported.
	* Cons: Older syntax, may be slower due to unnecessary overhead.
2. **Object.keys().forEach()**:
	* Pros: Modern syntax, concise.
	* Cons: May incur additional overhead due to method call, less efficient than other options.
3. **Object.keys().for...of loop**:
	* Pros: More modern syntax, avoids `forEach()` overhead.
	* Cons: Requires some understanding of the `Object.keys()` method and traditional loops.
4. **Object.entries().for...of loop**:
	* Pros: Provides direct access to keys and values.
	* Cons: Less intuitive than other options, requires knowledge of `Object.entries()`.

**Library Usage**

None of the test cases explicitly use any libraries beyond JavaScript's built-in features.

**Special JS Features or Syntax**

The benchmark does not mention any special JS features or syntax, such as `let` or `const`, `async/await`, or modern JavaScript modules (e.g., ES6 imports/export).

**Other Alternatives**

For iterating over objects in JavaScript, other alternatives might include:

* Using a library like Lodash or Ramda to provide additional utility functions.
* Utilizing object iteration methods provided by frameworks like React or Angular.
* Leveraging `for...of` loops with `Object.entries()` and other methods.

These alternative approaches may offer different performance characteristics, trade-offs in readability, or use cases that require specific features.

Related benchmarks:

for-in vs Object.keys.forEach vs Object.keys with for loop vs Object.entries (version: 0)

Comparing performance of: for-in vs Object.keys.forEach vs Object.keys with for of loop vs Object.entries

Created: 5 years ago by: Guest

Jump to the latest result

for-in

Object.keys.forEach

Object.keys with for of loop

Object.entries

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):