Benchmark: Map.has vs Map.get check if the key exists

Tests:

has
const map = new Map(); map.set("foo", 1); for(let i = 0; i < 10000; i ++){ if(map.has("foo")){ } }
get
const map = new Map(); map.set("foo", 1); for(let i = 0; i < 10000; i ++){ if(map.get("foo")){ } }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
has
get

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/125.0.0.0 Safari/537.36

Browser/OS: Chrome 125 on Windows

View result in a separate tab

Test name	Executions per second
has	37282.6 Ops/sec
get	139336.7 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 and analyze what's being tested on MeasureThat.net.

**Benchmark Overview**

The benchmark in question is designed to compare two approaches for checking if a key exists in a Map object: `map.has()` and `map.get()`. A Map is a data structure that stores mappings between keys and values. In this case, the map contains only one key-value pair, "foo" with value 1.

**Options Compared**

The benchmark tests two options:

1. **`map.has('foo')`**: This approach checks if the key 'foo' exists in the map using the `has()` method.
2. **`map.get('foo')`**: This approach attempts to retrieve the value associated with the key 'foo' using the `get()` method.

**Pros and Cons of Each Approach**

**`map.has('foo')`**

Pros:

* More efficient since it only checks if the key exists, without retrieving its associated value.
* Can be faster for large maps or when only checking existence.

Cons:

* May not work as expected if the map is modified concurrently (e.g., another thread inserts a new key).
* Returns `false` if the map is empty, whereas `map.get()` returns `undefined`.

**`map.get('foo')`**

Pros:

* Works consistently even when the map is modified concurrently.
* Returns `undefined` if the map does not contain the key.

Cons:

* May be slower since it retrieves the associated value, even if only to check existence.
* Can lead to unnecessary memory allocation and garbage collection if the retrieved value is not used.

**Other Considerations**

When using `map.has('foo')`, consider that this method may not work as expected if the map's underlying data structure is modified concurrently. In contrast, `map.get('foo')` is more robust in this regard but might be slower due to unnecessary retrievals.

If you need to frequently check for key existence without retrieving its associated value, `map.has('foo')` might be a better choice. However, if you want to ensure consistent behavior even when modifying the map concurrently, or need to retrieve the associated value occasionally, `map.get('foo')` is likely more suitable.

**Library and Special JS Feature**

In this benchmark, no external library is used beyond JavaScript's built-in `Map` data structure. There are no special JavaScript features or syntaxes involved, so you can easily reproduce this benchmark using a standard web browser or Node.js environment with the JavaScript engine enabled.

**Other Alternatives**

Alternatives to measure execution time for small scripts like this include:

* Browser developer tools (e.g., Chrome DevTools' Benchmarking panel)
* Node.js `performance.now()` function
* Online testing platforms like CodePen, JSFiddle, or Repl.it

Keep in mind that these alternatives might not provide the same level of control as MeasureThat.net's custom benchmarking environment.

Related benchmarks:

Map.has vs Map.get check if the key exists (version: 0)

Comparing performance of: has vs get

Created: 2 years ago by: Guest

Jump to the latest result

has

get

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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