Benchmark: Map vs Object 12345

Script Preparation code:

const map = new Map();
const obj = {};

const count = 1000
const l = []

for (let x=0; x<=count; x++) {
  l.push([[''+x, x]])
}

function bMap() {
  'use strict'
  for (let j = 0; i+j < count; j++){
    for (let i = 0; i < count; i++) {
      const [k, v] = l[i]
      const n = map.get(k)
      if (n !== undefined) {
          map.set(k, v)
      } else {
          map.set(k, n+j)
      }
    }
  }
}

function bObj() {
  'use strict'
  for (let j = 0; i+j < count; j++){
    for (let i = 0; i < count; i++) {
      const [k, v] = l[i]
      const n = obj[k]
      if (n !== undefined) {
          obj[k] = v
      } else {
          obj[k] = n+j
      }
    }
  }
}

Tests:

Map lookup
bMap()
Obj lookup
bObj()

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:

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

LLMs can make mistakes. Check important info.

Let's dive into the benchmark and explain what's being tested.

**Benchmark Definition**

The provided JSON represents a JavaScript microbenchmark that compares the performance of using a `Map` data structure versus an object (`obj`) for lookup operations.

**What is tested?**

In this benchmark, two functions are defined:

1. `bMap()`: This function iterates over an array of key-value pairs and uses a `Map` to store the values. It checks if a key already exists in the map by using the `get()` method, and if not, it sets the value for that key.
2. `bObj()`: This function is similar to `bMap()`, but instead of using a `Map`, it uses an object (`obj`) for lookup operations.

**Options compared**

The two functions are compared in terms of their performance when performing lookup operations on large datasets.

**Pros and Cons of each approach:**

1. **Map (`bMap()`)**:
	* Pros:
		+ Fast lookups using `get()` method.
		+ Efficient use of memory for large datasets.
	* Cons:
		+ May have slower initial creation time compared to objects.
2. **Object (`bObj()`)**:
	* Pros:
		+ Faster initial creation time compared to Maps.
		+ Often preferred for simple key-value stores due to simplicity and readability.
	* Cons:
		+ Slower lookups using property access (e.g., `obj[key]`).
		+ May require more memory allocations for large datasets.

**Other considerations:**

* The benchmark uses a simple dataset with 10,000 key-value pairs, which is relatively small compared to typical use cases. Real-world scenarios often involve larger datasets, and the performance differences between Maps and objects might be less pronounced.
* The `Map` implementation used in the benchmark likely provides some level of caching or optimization for repeated lookups, which could affect its performance characteristics.

**Library and purpose**

The `Map` data structure is a built-in JavaScript object that allows you to store key-value pairs in an efficient and scalable way. It provides fast lookups using the `get()` method, which returns the value associated with a given key or `undefined` if no such key exists.

In contrast, objects are a more traditional JavaScript data structure for storing key-value pairs, but they may not provide the same level of performance and scalability as `Map`.

**Special JS features or syntax**

The benchmark uses some advanced JavaScript features, such as:

* Arrow functions (`() => { ... }`) in the benchmark preparation code.
* Template literals (`'' + x` and `'[' + k + ', ' + v]`).
* The `for...of` loop (not explicitly used, but implied by the array iteration).

These features are widely supported in modern JavaScript engines, including those used by MeasureThat.net.

**Alternatives**

There are other data structures available in JavaScript that might be worth considering depending on your specific use case:

1. **WeakMaps**: Similar to `Map`, but with additional features for handling weak references and garbage collection.
2. **Set**: An unordered collection of unique values, which can be useful for fast membership testing and set operations.
3. **SortedMaps** or **SortedSets**: Data structures that maintain a sorted order of key-value pairs or elements.

Keep in mind that the choice of data structure ultimately depends on your specific requirements and constraints.

Related benchmarks:

Map vs Object 12345 (version: 0)

Lookup of map vs object

Comparing performance of: Map lookup vs Obj lookup

Created: 7 years ago by: Guest

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):