Benchmark: Map vs Object - Multiple keys

Script Preparation code:

var map = new Map();
var obj = {};

map.set('1', 5);
map.set('2', 5);
map.set('3', 5);
obj['1'] = 5;
obj['2'] = 5;
obj['3'] = 5;

var i = 0, count = 1000, a, index;

Tests:

Map lookup
index = 1; for (i = 0; i < count; i++) { a = map.get(index + ''); index++; index = index === 4 ? 1 : index; }
Obj lookup
index = 1; for (i = 0; i < count; i++) { a = obj[index + '']; index++; index = index === 4 ? 1 : index; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Map lookup
Obj lookup

Fastest: N/A

Slowest: N/A

Latest run results:

No previous run results

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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 benchmark.

**Benchmark Definition**

The benchmark is designed to compare the performance of two data structures: JavaScript Maps and objects (specifically, arrays with bracket notation) when used as lookup tables.

Here's what's being compared:

1. **Map**: A Map is a data structure that stores key-value pairs. In this case, the keys are strings, and the values are integers.
2. **Object** (with array index syntax): An object is an alternative to Maps in JavaScript. However, instead of using `map.get()` or `obj[key]`, we're using bracket notation (`obj[index + '']`) to access values.

**Pros and Cons**

Using a Map as a lookup table has several advantages:

* **Fast lookups**: Maps provide O(1) lookups on average, making them suitable for large datasets.
* **Efficient memory usage**: Maps use less memory compared to objects when dealing with large numbers of key-value pairs.

However, using an object with bracket notation has some drawbacks:

* **Slower lookups**: Bracket notation can be slower than direct property access (`map.get()` or `obj[key]`) because it involves string manipulation and potentially multiple DOM lookups (if accessing properties via the DOM).
* **Less memory efficient**: When dealing with large numbers of key-value pairs, objects using bracket notation can consume more memory compared to Maps.

**Special JavaScript Feature**

In this benchmark, we're leveraging a feature called "string concatenation" in JavaScript. Specifically, `index + ''` is used to convert the integer `index` into a string. This is a common pattern when working with arrays or objects and need to use bracket notation as a key.

Now, let's talk about alternative approaches:

* **Using `Object.entries()`**: Instead of using bracket notation, you could iterate over an object's entries using `Object.entries()`. This method is more efficient than string concatenation for large datasets.
* **Using `Map.prototype.get()` with a loop**: Another alternative is to use `Map.prototype.get()` in a loop, which can be faster than direct lookups.

To prepare this benchmark, you would:

1. Create a JavaScript file and copy the Script Preparation Code into it.
2. Run the script using a web browser or Node.js (depending on your preference).
3. Open MeasureThat.net and create a new benchmark.
4. Paste the Benchmark Definition JSON into the "Benchmark Definition" field.
5. Click "Run" to execute the benchmark.

You can also modify the Script Preparation Code to experiment with different approaches, such as using `Object.entries()` or `Map.prototype.get()`.

Related benchmarks:

Map vs Object - Multiple keys (version: 2)

Lookup of map vs object with multiple keys

Comparing performance of: Map lookup vs Obj lookup

Created: 3 years ago by: Registered User

Jump to the latest result

Map lookup

Obj lookup

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

No previous run results

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