Benchmark: Object.keys() allocation

Script Preparation code:

var obj = {0: '1', 1: '2', 2: '3', 3: '4', 4: '5'};

Tests:

Execute everytime
for (let i = 0; i < 100; i++) { let a = Object.keys(obj); }
Execute once
let b = Object.keys(obj); for (let i = 0; i < 100; i++) { let a = b; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Execute everytime
Execute once

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/126.0.0.0 Safari/537.36

Browser/OS: Chrome 126 on Windows

View result in a separate tab

Test name	Executions per second
Execute everytime	26182.1 Ops/sec
Execute once	2227125.2 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 for any developer, and MeasureThat.net provides a great platform to do so. Let's dive into the benchmark you provided.

**Benchmark Definition**

The benchmark definition represents a single test case. In this case, there are two test cases: "Execute everytime" and "Execute once". The script preparation code is the same for both test cases:

```javascript
var obj = {0: '1', 1: '2', 2: '3', 3: '4', 4: '5'};
```

This code creates an object `obj` with five properties, each containing a string value.

**Test Cases**

There are two test cases:

1. **Execute everytime**: This test case executes the following code inside an infinite loop:
   ```javascript
for (let i = 0; i < 100; i++) {
    let a = Object.keys(obj);
}
```
   In each iteration, it retrieves the keys of `obj` using `Object.keys()` and assigns the result to variable `a`.

2. **Execute once**: This test case executes the following code:
   ```javascript
let b = Object.keys(obj);

for (let i = 0; i < 100; i++) {
    let a = b;
}
```
   First, it retrieves the keys of `obj` using `Object.keys()` and assigns the result to variable `b`. Then, in each iteration, it assigns the value of `b` to variable `a`.

**Comparison**

The two test cases differ in when the execution of `Object.keys(obj)` is done. In the "Execute everytime" case, the execution is performed inside a loop, whereas in the "Execute once" case, it is executed before the loop.

**Pros and Cons**

1. **Execute everytime**: This approach has an overhead due to the repeated calls to `Object.keys(obj)`. However, the repeated execution might result in better cache locality since the data is always available.
   - Pros: Better cache locality
   - Cons: Higher overhead due to repeated function calls

2. **Execute once**: In this case, the initial call to `Object.keys(obj)` has a higher overhead compared to the "Execute everytime" approach. However, after that, each iteration becomes very efficient since `b` is already available.
   - Pros: Lower overhead for repeated iterations
   - Cons: Higher overhead for the initial call

**Library and Special JS Features**

There are no external libraries used in this benchmark. However, it does utilize some JavaScript syntax features:

- The use of template literals (`var obj = {0: '1', 1: '2', 2: '3', 3: '4', 4: '5'};`) to create the object.
- The usage of `Object.keys()` to retrieve the keys of an object.

**Other Alternatives**

If you want to measure JavaScript performance, here are some alternatives:

- **V8 Perftools**: An integrated development environment (IDE) that includes a built-in profiler for measuring JavaScript performance.
- **Chrome DevTools**: A set of web developer tools built into Google Chrome. They provide various profiling and performance metrics.
- **Node.js Performance Tools**: Node.js provides a range of built-in modules, including `v8_inspector`, which can be used to monitor performance in JavaScript.

I hope this explanation helps you understand the benchmark provided on MeasureThat.net!

Related benchmarks:

Object.keys() allocation (version: 0)

Comparing performance of: Execute everytime vs Execute once

Created: one year ago by: Guest

Jump to the latest result

Execute everytime

Execute once

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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