Benchmark: object key vs indexof

Script Preparation code:

var a = [{"id":7,"h":76},{"id":4,"h":34},{"id":9,"h":89}];
var b = [];
for(var i=0;i<a.length;i++)b[i] = a[i].id;
var c = [];
for(var i=0;i<a.length;i++)c[a[i].id] = a[i];

Tests:

loop lookup
for(var i in a)if(i.id==9)return i;
array indexed
return a[b.indexOf(9)];
key lookup
return c[9];

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
loop lookup
array indexed
key lookup

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/122.0.0.0 Safari/537.36

Browser/OS: Chrome 122 on Windows

View result in a separate tab

Test name	Executions per second
loop lookup	2279662.2 Ops/sec
array indexed	3908394.0 Ops/sec
key lookup	7734552.0 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 provided benchmarking test cases and explain what's being tested.

**Benchmark Overview**

The primary goal of this benchmark is to compare three different approaches for accessing data in an object or array:

1. **Array Indexing**: Using the `indexOf` method to find the index of a value in an array.
2. **Key Lookup**: Directly accessing a property by its key (in this case, `a[i].id`) using dot notation or bracket notation (`c[a[i].id] = a[i];`).
3. **Loop Lookup**: Iterating through an array or object to find the desired value.

**Library and Special JS Features**

None of the benchmarking tests explicitly use any libraries or special JavaScript features beyond basic syntax (e.g., `for` loops, dot notation, bracket notation).

**Benchmark Test Cases**

The three test cases are designed to measure the performance of each approach:

1. **Loop Lookup**: The first test case uses a loop to iterate through an array (`a`) and checks if the current element's `id` property matches 9.
2. **Array Indexed**: The second test case uses the `indexOf` method to find the index of 9 in the array `a`, then uses that index to access the corresponding element in the array `c`.
3. **Key Lookup**: The third test case directly accesses the `id` property using bracket notation (`c[a[i].id] = a[i];`) to retrieve the value associated with each key.

**Comparison and Pros/Cons**

Here's a brief summary of each approach, their pros, and cons:

1. **Array Indexing (indexOf)**:
	* Pros: Fast lookup, efficient for large datasets.
	* Cons: Can be slower for small datasets or when using `toString()` or other methods on the value being searched.
2. **Key Lookup**:
	* Pros: Fast access to specific properties, suitable for object or array with unique keys.
	* Cons: May require more memory allocation and deallocation for large datasets, as it directly accesses the property value.
3. **Loop Lookup**:
	* Pros: Simple to implement, no additional memory overhead.
	* Cons: Generally slower than other approaches due to iteration, especially for large datasets.

**Other Alternatives**

If not using `indexOf`, alternative methods for finding an element in an array could be:

1. `Array.prototype.includes()`: A more modern and efficient method (introduced in ECMAScript 2015).
2. `Binary Search**: An optimized algorithm for finding an element in a sorted array, which is faster but more complex to implement.

For key lookup, alternative methods include:

1. Using `Object.keys()` or `Object.values()` to iterate over object properties.
2. Utilizing data structures like hash tables (e.g., using `Map` objects) for fast lookups.

**Benchmarking Insights**

The benchmark results show that the **Key Lookup** approach is the fastest, followed by **Array Indexing**, and then **Loop Lookup**. This outcome may vary depending on the specific dataset size, browser, and version.

Related benchmarks:

object key vs indexof (version: 0)

Comparing performance of: loop lookup vs array indexed vs key lookup

Created: 9 years ago by: Guest

Jump to the latest result

loop lookup

array indexed

key lookup

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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