Benchmark: Object entries vs forin

Script Preparation code:

var arrayValue = [{a: 30310}, {b: 100303}, {c: 3040494}]
var objectValue = { a: 30310, b: 100303, c: 3040494}

Tests:

Object.entries
Object.entries(objectValue).forEach(() => {})
for...in
for(var k in objectValue) { var v = objectValue[k]; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Object.entries
for...in

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: one year ago)

User agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:137.0) Gecko/20100101 Firefox/137.0

Browser/OS: Firefox 137 on Ubuntu

View result in a separate tab

Test name	Executions per second
Object.entries	14162953.0 Ops/sec
for...in	43702220.0 Ops/sec

Autogenerated LLM Summary (model llama3.2:3b, generated one year ago):

LLMs can make mistakes. Check important info.

Measuring JavaScript performance is an essential task, especially when optimizing code for different browsers and environments.

The provided JSON represents a benchmark test case on MeasureThat.net, which compares the performance of two approaches to iterate over object entries: `Object.entries()` and `for...in`.

**Object.entries()**

`Object.entries()` is a modern JavaScript method introduced in ECMAScript 2015 (ES6). It returns an array of key-value pairs for the given object. The test case creates an object `objectValue` with three properties (`a`, `b`, and `c`) and then uses `Object.entries()` to iterate over its entries.

**for...in**

The traditional `for...in` loop is a legacy way to iterate over object properties. It was widely used before the introduction of `Object.entries()`. The test case uses `var k in objectValue` to iterate over the object's properties, where `k` takes on the property names.

**Comparison and Pros/Cons**

The benchmark tests both approaches to see which one is faster. Here are some pros and cons of each approach:

*   **Object.entries()**:
    *   Pros:
        *   More modern and efficient (due to optimized native implementation)
        *   Less prone to errors, as it uses a standardized method
    *   Cons:
        *   May not work in older browsers or environments that don't support ES6
*   **for...in**:
    *   Pros:
        *   Works across most browsers and environments (including older ones)
        *   Less dependent on modern JavaScript features
    *   Cons:
        *   Less efficient due to the need for manual property access and iteration
        *   More prone to errors, as it's a legacy method

**Library Usage**

There is no library used in this test case. The `Object.entries()` method is a built-in part of modern JavaScript.

**Special JS Features/Syntax**

This benchmark does not rely on any special JavaScript features or syntax beyond the comparison between `Object.entries()` and `for...in`. Both approaches are well-established and widely supported.

**Alternative Approaches**

Other alternatives for iterating over object entries include:

*   **for...of**: A newer method introduced in ECMAScript 2017 (ES7) that allows iteration over arrays or iterables. However, it's not directly applicable to objects.
*   **Object.keys() + for...of**: Using `Object.keys()` to get an array of property names and then iterating over it using a `for...of` loop.

Keep in mind that performance optimizations often depend on the specific use case and target audience. This benchmark provides a general comparison between two well-established methods, allowing developers to make informed decisions about their own code.

Related benchmarks:

Object entries vs forin (version: 0)

Comparing performance of: Object.entries vs for...in

Created: 4 years ago by: Guest

Jump to the latest result

Object.entries

for...in

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated one year ago):