Benchmark: Javascript Object vs Array.indexOf

Script Preparation code:

var object = { A : "A", B : "B", C : "C" };
var array  = [ "A", "B", "C" ];

Tests:

indexOf
array.indexOf("C");
Object
object["C"]

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
indexOf
Object

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/135.0.0.0 Safari/537.36

Browser/OS: Chrome 135 on Windows

View result in a separate tab

Test name	Executions per second
indexOf	84928560.0 Ops/sec
Object	142337488.0 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down the benchmark and its components.

**What is tested?**

The provided JSON represents a JavaScript microbenchmark that compares two approaches:

1. **Object property access**: `object[\"C\"]`
2. **Array index of**: `array.indexOf(\"C\")`

Both tests aim to measure how fast each approach can execute, but they serve different purposes.

**Options compared:**

* Object property access (`object[\"C\"]`):
	+ Pros:
		- Directly accesses the desired property in an object.
		- Might be faster for large objects or when accessing a specific property is common.
	+ Cons:
		- Can lead to slower performance if the object is large and not optimized for property access (e.g., due to overhead of JavaScript engine's lookup mechanisms).
		- May not work as expected with certain types of objects (e.g., arrays, functions) or in specific browsers/engines.
* Array index of (`array.indexOf(\"C\")`):
	+ Pros:
		- Efficiently searches for a value in an array.
		- Works well for large arrays and can handle edge cases like duplicate values.
	+ Cons:
		- Can be slower than object property access when searching for the first occurrence of a value (as it has to iterate through the entire array).
		- May not work as expected with certain types of arrays (e.g., sparse arrays) or in specific browsers/engines.

**Library and purpose:**

There is no explicit library mentioned in the benchmark definition. However, `array.indexOf()` is a built-in JavaScript method that uses the `Map` data structure internally to perform fast searches.

**Special JS feature or syntax:**

There are no special JavaScript features or syntax mentioned in the benchmark definition. The tests only use basic JavaScript syntax and do not include any experimental or deprecated features.

**Other alternatives:**

If you want to compare different approaches, here are a few more options:

1. **Using `in` operator**: `object['C']`
2. **Using bracket notation with optional chaining**: `object?.C`
3. **Using a for...of loop**: `for (const value of object) { if (value === 'C') break; }`

Each of these alternatives has its own trade-offs and might be faster or slower than the original benchmark in different scenarios.

Keep in mind that microbenchmarks can have various factors affecting their results, such as:

* Hardware and operating system specifics
* Browser engine optimizations
* JavaScript version and engine versions
* Object creation and size

When interpreting benchmark results, it's essential to consider these factors and not just the raw execution time numbers.

Related benchmarks:

Javascript Object vs Array.indexOf (version: 0)

Comparing performance of: indexOf vs Object

Created: 4 years ago by: Guest

Jump to the latest result

indexOf

Object

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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