Benchmark: let vs const v1 - MeasureThat.net

Script Preparation code:

function send_nodeagg(aggr) { return aggr.get('key')}

Tests:

let
let nagg = new Map(); let nodeagg = {aggr: nagg, send: send_nodeagg, currdt: '', currhost: '', currmap: new Map()}; nodeagg.send(nodeagg.aggr);
const
const nagg = new Map(); const nodeagg = {aggr: nagg, send: send_nodeagg, currdt: '', currhost: '', currmap: new Map()}; nodeagg.send(nodeagg.aggr);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
let
const

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 2 years ago)

User agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/118.0.0.0 Safari/537.36

Browser/OS: Chrome 118 on Linux

View result in a separate tab

Test name	Executions per second
let	4108724.8 Ops/sec
const	4147894.0 Ops/sec

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 on MeasureThat.net.

**Benchmark Overview**

The provided benchmark measures the performance difference between using `let` and `const` in JavaScript, specifically when creating objects with nested properties. The test case creates an object `nodeagg` that contains a map (`nagg`) and calls a function `send_nodeagg` on it.

**Options Compared**

Two options are being compared:

1. **Let**: The first option uses the `let` keyword to declare the `nagg` variable, which is then used as part of an object.
2. **Const**: The second option uses the `const` keyword to declare the `nagg` variable, which is also used as part of an object.

**Pros and Cons**

*   **Let**: When using `let`, JavaScript resolves the reassignment issue by always declaring a new variable when assigning a value to it. This means that if you assign a new value to `nagg` later on in your code, a new map will be created. However, this can lead to performance implications due to the overhead of creating a new object.
*   **Const**: When using `const`, JavaScript also resolves the reassignment issue by declaring a constant variable when assigning a value to it. This means that once a value is assigned to `nagg`, it cannot be reassigned to, and any subsequent updates will modify the original map. However, this can lead to limitations in flexibility when working with data structures.

**Library and Purpose**

In the benchmark preparation code, the following library is used:

*   `Map`: A JavaScript object that preserves the order of insertion, allowing for efficient key-value pair lookups.
*   `send_nodeagg` function: This function takes an argument (`aggr`) which is expected to be a Map. It returns the value of this map using the `get()` method.

**Special JS Feature/Syntax**

There is no special JavaScript feature or syntax being used in this benchmark that would affect its execution or interpretation.

**Other Alternatives**

Other alternatives for this benchmark could include:

*   Using `var` instead of `let` and `const`, which would also declare a variable but with different scope and reassignment rules.
*   Creating objects using array literals (`[]`) or object literals (`{}`) instead of maps, to test performance characteristics related to these data structures.
*   Adding additional operations or complexity to the `send_nodeagg` function or the object creation process to simulate real-world scenarios.

In conclusion, this benchmark measures the performance difference between using `let` and `const` when creating objects with nested properties. The results highlight the reassignment implications of each keyword, which can impact performance in certain cases.

Related benchmarks:

let vs const v1 (version: 0)

Comparing performance of: let vs const

Created: 2 years ago by: Guest

Jump to the latest result

let

const

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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