Benchmark: Map vs Obj lookup test

Script Preparation code:

var map = new Map();
var obj = {};

map.set('a', 5);
obj['a'] = 5;

var i = 0, count = 100000, a;

Tests:

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

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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 the provided benchmark and explain what's being tested, compared, and some considerations.

**Benchmark Overview**

The test measures the performance difference between looking up values in a `Map` object versus an object literal (`obj`) in JavaScript. The goal is to determine which approach is faster for repeated lookups.

**Options Compared**

There are two options being compared:

1. **Map Lookup**: Using the `get()` method on a `Map` object to retrieve a value.
2. **Object Literal Lookup**: Using square bracket notation (`[]`) to access a property of an object literal (`obj`).

**Pros and Cons of Each Approach**

**Map Lookup (get() method)**

Pros:

* Fast, as it uses a hash table internally for efficient lookups
* Can handle large numbers of keys without significant performance degradation
* Allows for dynamic key values

Cons:

* May incur additional overhead due to the `get()` method call
* Requires the value associated with the key to be present in the map (if not, it returns `undefined`)

**Object Literal Lookup**

Pros:

* Fast, as it uses a simple array-based lookup mechanism
* Does not require the value associated with the key to be present in the object
* Can be more memory-efficient for sparse objects

Cons:

* May perform slower than `Map` lookups due to the overhead of accessing properties via square brackets
* Limited by the number of keys an object can hold without performance degradation

**Other Considerations**

* Both approaches rely on the underlying JavaScript engine's optimization and caching mechanisms, which can affect performance.
* The `get()` method on a `Map` object may use a more complex lookup algorithm than simple array-based access in objects.

**Library Used**

The test uses the built-in `Map` class, which is part of the ECMAScript standard. The `Map` class provides an efficient way to store and look up key-value pairs.

**Special JavaScript Feature/Syntax**

None mentioned in this specific benchmark. However, it's worth noting that the use of `Map` objects and modern JavaScript features like ES6 classes (`class`) might require a higher level of JavaScript knowledge for developers not familiar with these concepts.

**Alternatives**

For similar benchmarks, you can explore other comparison options:

* Using an array instead of `Map` or object literals
* Measuring performance with different data structures (e.g., sets, trees)
* Comparing lookup methods on arrays (e.g., `indexOf()`, `includes()`)

By running multiple iterations of these tests and considering various factors like caching, indexing, and memory allocation, developers can gain insights into the performance characteristics of their JavaScript applications.

Related benchmarks:

Map vs Obj lookup test (version: 0)

Lookup of map vs object

Comparing performance of: Map lookup vs Obj lookup

Created: 2 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):