Benchmark: Array vs object - MeasureThat.net

Script Preparation code:

var n = 100;
var a = [];
var obj = {};
for (var i=0; i<n; i++) {
  a[i] = i;
  obj["obj" + i] = i;
}

Tests:

Array
r = Math.floor(Math.random()*n); for (var i=0; i<n; i++) { if (a[i] == r) break; }
Object
r = Math.floor(Math.random()*n); var i = obj["obj"+r];

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Array
Object

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 and explain what's being tested, compared, and other considerations.

**Benchmark Definition**

The benchmark defines two test cases: "Array" and "Object". The goal is to measure which approach (using an array or an object) performs better in terms of execution speed.

**Script Preparation Code**

The script preparation code creates:

1. Two variables: `a` (an empty array) and `obj` (an empty object).
2. A loop that iterates `n` times (`100` in this case). In each iteration:
	* The current element in the array is set to its index (`i`).
	* The corresponding property name of the object is created as a string ("obj" + `i`) and assigned its value to be the same as the current element's index.

**Html Preparation Code**

There is no HTML preparation code provided, which means that this benchmark likely runs in a headless browser or on a server-side environment.

**Individual Test Cases**

The two test cases are:

1. "Array":
	* Generates a random number `r` between 0 and `n-1`.
	* Iterates the array until it finds an element with the generated value.
2. "Object":
	* Generates a random property name for the object based on the previous benchmark definition.
	* Retrieves the value of the corresponding property in the object.

**Comparison**

The benchmark compares the execution speed of these two approaches:

1. Using an array (`Array` test case)
2. Using an object (`Object` test case)

**Pros and Cons**

**Array approach:**

Pros:

* Typically faster for large datasets due to cache locality (modern JavaScript engines are optimized for arrays).
* Easier to implement and optimize.

Cons:

* Less intuitive for accessing elements, as indices are used instead of property names.
* May not be suitable for scenarios where property names are meaningful or have specific semantics.

**Object approach:**

Pros:

* More intuitive for accessing elements, as property names can provide additional context.
* Suitable for scenarios where property names have specific meanings or are descriptive.

Cons:

* Typically slower due to the overhead of creating and resolving property names at runtime.
* May be less cache-efficient than arrays.

**Other Considerations**

1. **Cache efficiency**: Modern JavaScript engines optimize array access, making it a faster option for large datasets. However, object property lookups can benefit from caching, especially when using hash tables or other data structures that minimize property name collisions.
2. **Property name semantics**: In certain scenarios, the meaning of property names can be critical (e.g., in JSON parsing or validation). Object-based access may provide a more intuitive and maintainable experience for developers.
3. **Iteration order**: Both array and object approaches can iterate over elements in a particular order (e.g., by index or by property name). The choice between the two often depends on the specific use case.

**Alternatives**

1. **Using Sets instead of Arrays/OBjects**: If you need to store unique values, consider using a Set data structure instead.
2. **Using DOM-based data structures**: For web applications, using DOM-based data structures (e.g., arrays in `Array.prototype`) can provide better performance and compatibility compared to traditional JavaScript arrays or objects.

Keep in mind that the choice between array and object approaches depends on the specific requirements of your project, including performance, readability, maintainability, and semantic consistency.

Related benchmarks:

Array vs object (version: 0)

Comparing performance of: Array vs Object

Created: 8 years ago by: Guest

Jump to the latest result

Array

Object

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):