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Map.has vs Map.get check if the key exists
(version: 0)
Comparing performance of:
has vs get
Created:
2 years ago
by:
Guest
Go to the latest result
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>
Run tests (2)
Previous results
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Test case name
Result
has
get
Fastest:
N/A
Slowest:
N/A
Latest run results:
Run details:
(Test run date:
2 years 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
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<iframe src="https://measurethat.net/Embed?id=524976" width="100%" height="500px"></iframe>
get
139K/s
has
37K/s
View exact numbers
Test name
Executions per second
✓
get
139,337 Ops/sec
has
37,283 Ops/sec
Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
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.
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