Benchmark: Map has vs get - MeasureThat.net

Script Preparation code:

var m = new Map([['test', 123]]);
var keys = ['test', 'test2'];

Tests:

has
keys.map(k => m.has(k) ? m.get(k) : k);
get
keys.map(k => m.get(k) ?? k);

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: 11 months ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:139.0) Gecko/20100101 Firefox/139.0

Browser/OS: Firefox 139 on Mac OS X 10.15

View result in a separate tab

Test name	Executions per second
has	67641984.0 Ops/sec
get	54718412.0 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down what's being tested in this JavaScript microbenchmark.

**Benchmark Overview**

The benchmark compares two approaches to accessing values from a `Map` object: `m.has(k)` and `m.get(k)`. Both methods are used to retrieve the value associated with a key (`k`) from the map. The difference lies in how they handle cases where the key is not present in the map.

**Options Being Compared**

Two options are being compared:

1. **`has`**: This method returns `true` if the key is present in the map, and `false` otherwise.
2. **`get`**: This method returns the value associated with the key if it exists, or a default value (`undefined` in this case) if the key does not exist.

**Pros and Cons**

Here are some pros and cons of each approach:

* **`has`**:
	+ Pros:
		- Can be faster since it only checks for presence.
		- May be more efficient for large maps where `get` would need to iterate over all keys.
	+ Cons:
		- Returns a boolean value, which may not be suitable for all use cases.
		- If you're expecting the return value to be a specific truthy value (e.g., `true`), this approach can lead to unnecessary conditionals.
* **`get`**:
	+ Pros:
		- Returns the actual value associated with the key, if it exists.
		- Can be more convenient for some use cases where you need to handle the actual value.
	+ Cons:
		- May require more iterations over keys since `has` only checks presence.
		- May be slower due to the additional lookup.

**Library Usage**

There is no explicit library usage in this benchmark. However, it's worth noting that `Map` objects are a built-in JavaScript API.

**Special JS Feature/Syntax**

The benchmark uses arrow functions (`k => m.has(k) ? m.get(k) : k`) and template literals (`"keys.map(k => m.get(k) ?? k);"`). These features are supported in modern JavaScript environments, including Chrome 89. If you're running this code in an older environment, these syntaxes might not be available.

**Other Considerations**

The benchmark appears to focus on the performance differences between `has` and `get`. However, it's also worth considering other factors that might affect performance or readability, such as:

* The size of the map: How many keys does the map have? If it's very large, `has` might be faster.
* The type of data stored in the map: If the values are mostly sparse (i.e., most keys don't have associated values), `get` might be slower due to unnecessary lookups.

**Alternatives**

If you're looking for alternative approaches or want to explore other optimizations, consider the following:

* Use a more advanced data structure, such as an `Object` with multiple properties.
* Implement a custom lookup function that combines the benefits of both `has` and `get`.
* Profile your code using tools like Chrome DevTools or JavaScript Profiler to identify performance bottlenecks.

Keep in mind that optimizations should be driven by real-world use cases and performance requirements. This benchmark seems to focus on understanding the inherent differences between `has` and `get`, rather than optimizing for a specific scenario.

Related benchmarks:

Map has vs get (version: 0)

Comparing performance of: has vs get

Created: 5 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):