Benchmark: Object lookup vs switch statement

Script Preparation code:

var str = 'abc';
str = str.charAt(Math.floor(Math.random() * 3));

var objLiteral = {
    a: function() {
        console.log('A');
    },
    b: function() {
        console.log('B');
    },
    c: function() {
        console.log('C');
    }
}

Tests:

Switch
switch (str) { case 'a': console.log('A'); break; case 'b': console.log('B'); break; case 'c': console.log('C'); break; }
Object lookup
objLiteral[str]();

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Switch
Object lookup

Fastest: N/A

Slowest: N/A

Latest run results:

No previous run results

This benchmark does not have any results yet. Be the first one to run it!

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 their pros and cons.

**Benchmark Overview**

The benchmark measures the performance difference between using a `switch` statement and an object lookup (via bracket notation) to determine which branch to execute. The script preparation code generates a random string (`str`) that will be used as input for both approaches.

**Script Preparation Code**

```javascript
var str = 'abc';
str = str.charAt(Math.floor(Math.random() * 3));
```

This code sets up the input string `str` by randomly selecting one of three possible values: `'a'`, `'b'`, or `'c'`.

**Object Literal Definition**

```javascript
var objLiteral = {
    a: function() { console.log('A'); },
    b: function() { console.log('B'); },
    c: function() { console.log('C'); }
};
```

This defines an object `objLiteral` with three properties (`a`, `b`, and `c`) each associated with a different logging function.

**Benchmark Definition**

The benchmark has two individual test cases:

1. **Switch**

```javascript
switch (str) {
    case 'a': console.log('A'); break;
    case 'b': console.log('B'); break;
    case 'c': console.log('C'); break;
}
```

This code uses a `switch` statement to determine which branch to execute based on the value of the input string `str`.

2. **Object Lookup**

```javascript
objLiteral[str]();
```

This code uses bracket notation (`objLiteral[str]`) to dynamically access and execute the corresponding logging function for the randomly selected input value.

**Comparison**

The benchmark is designed to compare the performance of these two approaches:

*   **Switch Statement**: The traditional `switch` statement.
*   **Object Lookup**: Using object properties as dynamic dispatch targets.

**Pros and Cons**

Here's a brief overview of the pros and cons for each approach:

1.  **Switch Statement**:
    *   Pros: 
        *   Typically faster due to native compiler optimizations.
        *   Easier to read and understand, especially for simple cases.
    *   Cons:
        *   Less flexible, as it's limited to a specific set of predefined cases.

2.  **Object Lookup**:
    *   Pros:
        *   More flexible than `switch` statements, as you can add or remove properties dynamically.
        *   Can be more suitable for complex scenarios where the number of cases is large.
    *   Cons:
        *   Typically slower due to JavaScript's dynamic nature and potential overhead.
        *   May have performance penalties if not optimized properly.

**Other Considerations**

*   **Library Usage**: The benchmark does not explicitly use any libraries. However, in a real-world scenario, you might need to consider additional dependencies or external modules that could impact performance.
*   **Special JS Features**: There are no special JavaScript features mentioned in the provided code. If the benchmark were to include such features, it would be essential to understand their implications on performance.

**Alternatives**

If you're considering alternative approaches for similar use cases:

1.  **Array-based Dispatch**: Using an array of objects with corresponding functions can offer a compromise between `switch` statements and object lookup.
2.  **Function-based Dispatch**: Utilizing function pointers or function caches might provide better performance in certain scenarios.

However, the optimal approach depends on your specific requirements, codebase complexity, and performance constraints.

Related benchmarks:

Object lookup vs switch statement (version: 0)

Comparing performance of: Switch vs Object lookup

Created: 3 years ago by: Guest

Jump to the latest result

Switch

Object 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):