Benchmark: Map has vs Object hasOwnProperty 2

Script Preparation code:

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

Tests:

Map lookup
for (i = 0; i < count; i++) { a = map.has('a'); }
Obj lookup
for (i = 0; i < count; i++) { a = obj.hasOwnProperty('a'); }

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:

Run details: (Test run date: 9 months ago)

User agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/138.0.0.0 Safari/537.36

Browser/OS: Chrome 138 on Linux

View result in a separate tab

Test name	Executions per second
Map lookup	6240.9 Ops/sec
Obj lookup	6115.4 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 focuses on comparing the lookup performance of a `Map` versus an `Object` in JavaScript. Here's a detailed breakdown of what is being tested, the pros and cons of each approach, considerations, and alternatives.

### Benchmark Overview
The benchmark consists of two test cases that measure how quickly each data structure can determine the presence of a specific key. The focus is on:
1. **Map Lookup**: Using the built-in `Map` object.
2. **Object Lookup**: Using the traditional JavaScript `Object` method `hasOwnProperty`.

### Test Cases
1. **Map Lookup**:
   ```javascript
   for (i = 0; i < count; i++) {
      a = map.has('a');
   }
   ```
   - This test measures the performance of the `has` method from a `Map`, checking whether the key `'a'` exists in the `map`.

2. **Object Lookup**:
   ```javascript
   for (i = 0; i < count; i++) {
      a = obj.hasOwnProperty('a');
   }
   ```
   - This test measures the performance of the `hasOwnProperty` method on an object, also checking for the presence of the key `'a'`.

### Pros and Cons of Each Approach
#### Map
**Pros:**
- **Predictable Performance**: `Map` has consistent performance for inserts and lookups regardless of the number of keys.
- **Key Types**: Allows keys of any type (including objects), not just strings or symbols.
- **Iteration**: Maps maintain the insertion order of keys, making them suitable for ordered operations.

**Cons:**
- **Memory Overhead**: Has more overhead compared to plain objects due to its internal structure, which can lead to higher memory usage if small datasets are used.

#### Object
**Pros:**
- **Lightweight**: Objects can be more memory efficient for small datasets, particularly when using string keys.
- **Familiar Syntax**: The object literal notation is widely used and easily understood.

**Cons:**
- **Performance Degradation**: Lookup times can become unpredictable as the number of properties grows, especially if there are a lot of prototype properties.
- **Key Limitations**: Can only use strings and symbols as keys.

### Benchmark Results
The benchmark results showed:
- **Map Lookup**: ~2786.06 executions per second.
- **Object Lookup**: ~2777.11 executions per second.

While both methods performed similarly in this instance, the `Map` still provided a slight edge.

### Considerations
- **Use Case**: The choice between `Map` and `Object` should depend on the specific use case and dataset size. For larger or more complex datasets, `Map` is generally preferred for lookups. Conversely, for simpler or smaller datasets, using an `Object` may suffice.
- **Browser Variation**: Performance may vary significantly across different JavaScript engines or browser implementations, so it's essential to consider where the application will be used.

### Alternatives
Other alternatives for lookups include:
- **Set**: For checking the existence of values (no key/value pairs).
- **WeakMap and WeakSet**: These structures enhance memory management and garbage collection but have limitations in usability (e.g., keys must be objects).

### Conclusion
The benchmark effectively illustrates the performance differences between a `Map` and an `Object` for key lookups. Both data structures have their strengths and weaknesses, and the decision to use one over the other should consider the specific requirements of the application, including performance, memory usage, and ease of use.

Related benchmarks:

Map has vs Object hasOwnProperty 2 (version: 1)

Lookup of map vs object

Comparing performance of: Map lookup vs Obj lookup

Created: one year ago by: Guest

Jump to the latest result

Map lookup

Obj lookup

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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