Benchmark: test Map vs Object

Script Preparation code:

var map = new Map();
var obj = {};

map.set('a', 5);
obj['a'] = 5;

var i = 0, count = 10000, a;

Tests:

Map
for (i = 0; i < count; i++) { a = map.get('a'); map.set('b',1); }
Obj
for (i = 0; i < count; i++) { a = obj['a']; obj['b'] = 1 }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Map
Obj

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 7 months ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/18.6 Safari/605.1.15

Browser/OS: Safari 18 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
Map	16036.6 Ops/sec
Obj	220316.0 Ops/sec

Autogenerated LLM Summary (model gpt-4o-mini, generated one year ago):

LLMs can make mistakes. Check important info.

The benchmark defined in the provided JSON is a comparison between two JavaScript data structures: `Map` and plain JavaScript `Object`. The goal is to evaluate their performance, particularly in read and write operations.

### Comparison of Options
1. **Map**
   - **Construction**: `var map = new Map();`
   - **Benchmark Operations**:
     - Retrieving a value: `a = map.get('a');`
     - Setting a new value: `map.set('b', 1);`
   - **Advantages**:
     - `Map` maintains the insertion order of its elements.
     - It allows for any data type as keys, including objects and functions.
     - Typically provides better performance for frequently changing collections, particularly when the size is large.
   - **Disadvantages**:
     - Slightly higher memory overhead compared to objects, particularly for small datasets.
     - Set-up time can be marginally longer since it is a dedicated data structure.

2. **Object**
   - **Construction**: `var obj = {};`
   - **Benchmark Operations**:
     - Retrieving a value: `a = obj['a'];`
     - Setting a new value: `obj['b'] = 1;`
   - **Advantages**:
     - Simpler and more lightweight for basic key-value storage.
     - Houses various methods and properties directly available on objects.
     - Widely familiar to JavaScript developers and often sufficient for many use cases.
   - **Disadvantages**:
     - Does not maintain insertion order for keys (prior to ES6, though ES6 does guarantee insertion order for strings, it can still be less intuitive).
     - Only strings and symbols can be used as keys (a limitation when needing non-string keys).

### Benchmark Execution
The benchmark consists of running the defined operations in a loop (10,000 iterations) for both `Map` and `Object`.

1. **Map Execution Stats**:
   - **Executions Per Second**: 1114.79 (approx.)
   - **Test Name**: "Map"

2. **Object Execution Stats**:
   - **Executions Per Second**: 1201.59 (approx.)
   - **Test Name**: "Obj"

From these results, it’s observable that the `Object` implementation is slightly faster (1201.59 EPS) than the `Map` implementation (1114.79 EPS). This can be attributed to the added overhead that `Map` has in terms of its complexity and features compared to plain objects.

### Other Considerations
- **Use Cases**: The choice between `Map` and `Object` often depends on use case needs. If you require non-string keys, complex keys, or need to maintain order, prefer `Map`. Use `Object` for simpler key-value pairs or when leveraging prototype inheritance.
- **Alternatives**: If the performance benchmarks matter in high-performance situations, consider:
  - **WeakMap**: Useful for maintaining associations without preventing garbage collection when keys are no longer accessible.
  - **Arrays**: Depending on the use case, arrays can sometimes replace maps or objects, particularly for ordered lists of values.

In summary, the benchmark clearly highlights the performance differences between `Map` and `Object`, guiding developers in choosing the appropriate data structure based on their specific requirements while also outlining the pros and cons of each approach.

Related benchmarks:

test Map vs Object (version: 1)

Comparing performance of: Map vs Obj

Created: one year ago by: Guest

Jump to the latest result

Map

Obj

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model gpt-4o-mini, generated one year ago):