Benchmark: Iterating keys - MeasureThat.net

Script Preparation code:

var obj = {};

for(let i = 0; i < 10; i++) {
  obj["key" + i] = i;
}

function fn(num) {
  return num * 2;
}

Tests:

Object.keys(obj).forEach()
Object.keys(obj).forEach(key => fn(obj[key]));
for...in...
for(const key in obj) { fn(obj[key]); }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Object.keys(obj).forEach()
for...in...

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 break down the benchmark and explain what's being tested.

**Benchmark Definition**

The benchmark measures the performance of two approaches to iterate over an object's keys:

1. `Object.keys(obj).forEach(key => fn(obj[key]))`
2. `for(const key in obj) {fn(obj[key])}`

Both approaches are used with a sample JavaScript object `obj` that has 10 properties, each initialized with a value from 0 to 9.

**Options Compared**

The two options compared are:

1. **Using `Object.keys()` and `forEach()`**: This method uses the `Object.keys()` function to get an array of the object's keys, and then iterates over that array using the `forEach()` method.
2. **Using a traditional `for...in` loop**: This method uses a traditional `for` loop with the `in` operator to iterate over the object's properties.

**Pros and Cons**

**Using `Object.keys()` and `forEach():**

Pros:

* Concise and readable code
* Easy to understand for developers familiar with modern JavaScript

Cons:

* May have slower performance due to the overhead of creating an array of keys
* Requires a compatible browser or environment that supports `forEach()` on arrays (not all browsers)

**Using `for...in`:**

Pros:

* Often faster than using `Object.keys()` and `forEach()`, especially for large objects
* Works in older browsers that don't support `Object.keys()` or `forEach()`

Cons:

* Less readable code compared to the first approach
* Requires a good understanding of the `in` operator and how it works on objects

**Library Used**

There is no library used in this benchmark. The JavaScript object `obj` is created directly.

**Special JS Features/Syntax**

None of the approaches use any special JavaScript features or syntax. Both are standard, widely supported JavaScript methods.

**Other Alternatives**

If you wanted to compare these options with other alternatives, here are a few possibilities:

* Using a library like Lodash or Ramda, which provide more functional programming-style functions for iterating over objects.
* Using a more specialized loop or iteration construct, such as `for...of` or `while (true)` loops.

Keep in mind that the choice of iteration method depends on the specific requirements and constraints of your project. In general, if you need high-performance code and compatibility with older browsers, `for...in` might be a better choice. If readability and simplicity are more important, using `Object.keys()` and `forEach()` could be a better option.

Related benchmarks:

Iterating keys (version: 0)

Comparing performance of: Object.keys(obj).forEach() vs for...in...

Created: 3 years ago by: Guest

Jump to the latest result

Object.keys(obj).forEach()

for...in...

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):