Benchmark: print keys for-in vs object.keys

Script Preparation code:

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

Tests:

for-in
for (var i=10000; i > 0; i--) { const keys = [] for (var key in obj) { keys.push(key) } console.log(keys) }
Object.keys
for (var i=10000; i > 0; i--) { console.log(Object.keys(obj)) }

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.

The provided JSON represents two test cases for measuring the performance of JavaScript microbenchmarks on MeasureThat.net.

**Benchmark Description:**

Both test cases aim to measure the performance difference between using the traditional `for...in` loop and the `Object.keys()` method to iterate over the keys of an object. The object in question is a large one with 11 properties, all initialized with the value 1.

**Options Compared:**

The two options being compared are:

1. **Traditional `for...in` loop**: This approach uses a traditional loop with a manual iteration mechanism to access the object's properties.
2. **Object.keys() method**: This is a built-in JavaScript method that returns an array of a given object's own enumerable property names.

**Pros and Cons:**

*   **Traditional `for...in` loop**:
    *   Pros:
        *   More flexible and can be used for other iteration mechanisms, such as using a custom iterator or accessing the prototype chain.
        *   Can handle objects with inherited properties by including them in the iteration.
    *   Cons:
        *   May have performance issues due to the overhead of iterating over the object's properties manually.
        *   May not be as efficient as other methods, especially for large objects.
*   **Object.keys() method**:
    *   Pros:
        *   More efficient and faster than the traditional `for...in` loop for most use cases.
        *   Provides a more predictable and consistent iteration order.
    *   Cons:
        *   Only returns the own enumerable property names, which may not include inherited properties.

**Library Usage:**

In this benchmark, no specific library is used. However, MeasureThat.net likely uses some internal library or framework to execute the JavaScript code and measure its performance.

**Special JS Features/Syntax:**

There are no special JavaScript features or syntax used in this benchmark. The focus is on comparing two common iteration methods, which do not rely on any advanced JavaScript features.

**Other Alternatives:**

Some other alternatives for iterating over object properties include:

*   **Array.prototype.forEach()**: This method can be used to iterate over an array of property names and then access the corresponding object properties using bracket notation (e.g., `obj[key]`).
*   **for...of loop with Object.entries()**: This approach uses a new syntax for iterating over objects, which returns an array-like object containing the object's own enumerable property names as strings.

Related benchmarks:

print keys for-in vs object.keys (version: 0)

Comparing performance of: for-in vs Object.keys

Created: 3 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):