Benchmark: for-in vs object.keys (no console)

Script Preparation code:

var obj = {
  'a': 1,
  'b': 1,
  'c': 1,
  'd': 1,
  'e': 1,
  'f': 1,
  'g': 1
};

Tests:

for-in
var otherObj = {}; for (var i=10000; i > 0; i--) { for (var key in obj) { otherObj[key] = obj[key]; } }
Object.keys
var otherObj = {}; for (var i=10000; i > 0; i--) { Object.keys(obj).forEach(key => { otherObj[key] = obj[key]; }); }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
for-in
Object.keys

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.

Let's dive into the world of JavaScript microbenchmarks and explore what's being tested in this specific benchmark.

**Benchmark Definition**

The benchmark is comparing two approaches for iterating over an object's properties: `for-in` loop and using `Object.keys()` method. The objective is to measure which approach is faster, assuming that we need to assign the values of each property to another object (`otherObj`) 10,000 times.

**Options Compared**

There are two options being compared:

1. **`for-in` loop**: This traditional loop iterates over an object's properties using the `in` operator and assigns each value to a variable.
2. **`Object.keys()` method**: This modern approach uses an array of property names obtained from the `Object.keys()` method, which is then iterated over using `forEach()`, and each value is assigned to another object (`otherObj`).

**Pros and Cons**

**For-in loop:**

Pros:

* Widely supported across browsers
* Simple and straightforward implementation

Cons:

* Less efficient than modern approaches like `Object.keys()` due to its overhead in iterating over properties
* Can be slower for large objects due to the `in` operator's behavior (e.g., when properties are inherited from prototype chains)

**Object.keys() method:**

Pros:

* More efficient and modern approach, optimized for performance
* Reduces boilerplate code and avoids potential issues with `in` operator

Cons:

* Less widely supported across older browsers or those without modern JavaScript features
* May require additional libraries or polyfills if not supported natively by the browser

**Other Considerations**

Both approaches assume that we need to assign the values of each property to another object (`otherObj`). This is a common use case, but it's essential to consider other factors that might affect performance, such as:

* Object size and complexity
* Data type and value distribution (e.g., numeric, string, or boolean)
* Browser-specific optimizations or limitations

**Library Used**

In this benchmark, the `Object.keys()` method is used, which is a standard JavaScript API for retrieving an array of property names from an object. This library is not explicitly mentioned in the benchmark definition, as it's part of the modern JavaScript standard.

If we were to use other libraries or frameworks that provide similar functionality, they might be:

* Lodash (a popular utility library with `_.keys()` function)
* Ramda (a functional programming library with `R.keys()` function)

**Special JS Feature or Syntax**

In this benchmark, there's no special JavaScript feature or syntax being used beyond the standard JavaScript language. However, it's worth noting that some modern browsers and engines might have additional features or optimizations for certain types of loops or iteration approaches.

Overall, this benchmark provides a useful comparison between two common approaches for iterating over object properties in JavaScript, highlighting the benefits and trade-offs of using `for-in` versus `Object.keys()`.

Related benchmarks:

for-in vs object.keys (no console) (version: 0)

same as the other one but with assigning to other object instead of console.logging

Comparing performance of: for-in vs Object.keys

Created: 5 years ago by: Guest

Jump to the latest result

for-in

Object.keys

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):