Benchmark: Map vs Object Creation

Script Preparation code:

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

Tests:

Map
for (i = 0; i < count; i++) { if (!map.has(i)) { map.set(i,i); } }
Obj
for (i = 0; i < count; i++) { if (i in obj) { obj[i] = i; } }

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:

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

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Let's break down the provided JSON data and explain what is being tested.

**Benchmark Definition**

The benchmark definition describes two test cases: "Map" and "Obj". Both tests aim to measure the performance of inserting key-value pairs into different data structures.

*   **Object Creation**: The first step in both benchmarks creates an empty object (`obj`) and a new Map instance (`map`).
*   **Insertion Logic**: In the "Map" test, values are inserted using `map.set()`, while in the "Obj" test, values are inserted using object property assignment (`obj[i] = i;`). The logic for checking if an index already exists is different between the two tests.

**Options Compared**

The main options being compared in this benchmark are:

*   **Map**: Uses `map.set()` to insert values and checks if an index already exists using `has()`.
*   **Object**: Uses object property assignment (`obj[i] = i;`) and checks if an index already exists using the "in" operator (i.e., `i in obj`).

**Pros and Cons of Different Approaches**

Here's a brief summary:

*   **Map Approach**:
    *   **Pros**:
        *   More concise and expressive code.
        *   Built-in data structure with optimized insertion performance.
    *   **Cons**:
        *   May be slower due to additional bookkeeping for `has()` checks.
*   **Object Approach**:
    *   **Pros**:
        *   Can be faster since no extra overhead for `has()` checks.
        *   More control over code structure and logic.
    *   **Cons**:
        *   Requires manual management of existing property assignments.

**Library Used**

Neither the "Map" nor the "Obj" test uses any external libraries. Both rely on native JavaScript features:

*   Map: Built-in `Map` data structure in modern browsers and Node.js environments.
*   Object: Native object literals with array-like behavior.

**Special JS Feature or Syntax**

There is no specific JavaScript feature or syntax being used beyond what's standard for these benchmarks.

**Other Alternatives**

Some alternative approaches to inserting values into a map or object might involve using:

*   **Array**: Converting the data structure into an array and then performing indexing operations.
*   **Set**: Using `Set` data structures for unique key-value pair insertions, if applicable (not directly relevant here).
*   **Custom data structures**: Creating custom data structures to optimize performance.

However, these alternatives are not being used in this benchmark.

Related benchmarks:

Map vs Object Creation (version: 0)

Insertion to map vs object

Comparing performance of: Map vs Obj

Created: 4 years ago by: Guest

Jump to the latest result

Map

Obj

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):