Benchmark: Switch vs Object Lookup

Script Preparation code:

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

Tests:

Switch
switch (str) { case 'a': return 'A'; case 'b': return 'B'; case 'c': return 'C'; }
Object Literal
var objLiteral = { a: 'A', b: 'B', c: 'C' } objLiteral[str];

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Switch
Object Literal

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: one year ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/136.0.0.0 Safari/537.36

Browser/OS: Chrome 136 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
Switch	225870544.0 Ops/sec
Object Literal	219375152.0 Ops/sec

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

LLMs can make mistakes. Check important info.

I'd be happy to explain what's being tested in the provided JSON benchmark.

**Benchmark Overview**

The benchmark compares two approaches for looking up values in an object: using a `switch` statement and using an object literal with bracket notation (`objLiteral[str];`). The goal is to determine which approach is faster.

**Switch vs Object Lookup**

The `switch` statement is used in the first test case:
```javascript
switch (str) {
  case 'a': return 'A';
  case 'b': return 'B';
  case 'c': return 'C';
}
```
In this approach, the value of `str` is used as an index to look up a corresponding value in an object. The object contains three cases: one for each possible value of `str`.

On the other hand, the second test case uses an object literal with bracket notation:
```javascript
var objLiteral = {
  a: 'A',
  b: 'B',
  c: 'C'
}
objLiteral[str];
```
Here, the value of `str` is used to index into the `objLiteral` object and retrieve the corresponding value.

**Pros and Cons**

* **Switch Statement**
	+ Pros:
		- Can be faster for small numbers of cases due to branch prediction.
		- Can be more readable when dealing with a small, fixed number of cases.
	+ Cons:
		- Can be slower for large numbers of cases due to the overhead of the `switch` statement.
		- May not work well with dynamically generated case values.
* **Object Literal**
	+ Pros:
		- Faster for larger numbers of cases because it avoids the overhead of a `switch` statement.
		- More flexible and can handle dynamically generated case values.
	+ Cons:
		- Can be less readable when dealing with a large number of cases.
		- May not work well if the case value is not a valid key in the object.

**Library: None**

There are no external libraries used in this benchmark. The test cases only use built-in JavaScript features and data types.

**Special JS Feature: Object Literals**

The second test case uses an object literal, which is a feature introduced in ECMAScript 1999 (ES-3). An object literal is a way to create objects using the `object` keyword followed by property-value pairs enclosed in curly braces. In this case, the object literal is used with bracket notation (`objLiteral[str];`) to access its properties.

**Other Alternatives**

If you wanted to test other approaches for looking up values in an object, some alternatives could include:

* Using a `for...in` loop to iterate over the object's properties.
* Using the `hasOwnProperty()` method to check if a property exists before trying to access it.
* Using a `Map` data structure instead of an object literal.

However, these approaches may not be as natural or efficient for this specific use case.

Related benchmarks:

Switch vs Object Lookup (version: 0)

Comparing performance of: Switch vs Object Literal

Created: 3 years ago by: Guest

Jump to the latest result

Switch

Object Literal

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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