Benchmark: Holey, Preallocated vs Packed, Pushed 3

Script Preparation code:

var holey = new Array(1000);
var packed = [];
var value = undefined;
var object = { value };
var store;
for(let i = 0; i < 1000; i++) packed.push(undefined);

Tests:

Create holey
holey = new Array(1000)
Create packed (push)
var packed = []; for(let i = 0; i < 1000; i++) packed.push(undefined);
Create packed (assign)
var packed = []; for(let i = 0; i < 1000; i++) packed[i] = undefined;
Read holey
store = holey[100]
Read packed
store = packed[100]
Read object
store = object.value;
Read value
store = value
Math
1+1
Create empty
store = []
Create empty, set length
store = []; store.length = 1000;
Create empty, set last
store = []; store[999] = undefined;
Create holey, fill
store = new Array(1000).fill(undefined)

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Create holey
Create packed (push)
Create packed (assign)
Read holey
Read packed
Read object
Read value
Math
Create empty
Create empty, set length
Create empty, set last
Create holey, fill

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 2 years ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:104.0) Gecko/20100101 Firefox/104.0

Browser/OS: Firefox 104 on Windows

View result in a separate tab

Test name	Executions per second
Create holey	120976.5 Ops/sec
Create packed (push)	50176.6 Ops/sec
Create packed (assign)	53130.1 Ops/sec
Read holey	532384800.0 Ops/sec
Read packed	512848032.0 Ops/sec
Read object	527832032.0 Ops/sec
Read value	476539648.0 Ops/sec
Math	1022253504.0 Ops/sec
Create empty	63232652.0 Ops/sec
Create empty, set length	20049850.0 Ops/sec
Create empty, set last	107182.9 Ops/sec
Create holey, fill	71540.8 Ops/sec

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

LLMs can make mistakes. Check important info.

Measuring performance of different approaches to creating and accessing arrays in JavaScript is crucial for ensuring efficient code. Let's break down the benchmarked approaches.

**Approaches being compared:**

1. **Holey Array**: `var holey = new Array(1000);`
2. **Packed Array (Push)**: `var packed = [];\r\nfor(let i = 0; i < 1000; i++) packed.push(undefined);`
3. **Packed Array (Assign)**: `var packed = [];\r\nfor(let i = 0; i < 1000; i++) packed[i] = undefined;`
4. **Object Access**: `var object = { value }; var store = object.value;`
5. **Direct Variable Access**: `var store = undefined;`
6. **Empty Array Creation**: `var store = []`
7. **Empty Array with Length Set**: `var store = []; store.length = 1000;`
8. **Empty Array with Last Element Set**: `var store = []; store[999] = undefined;`
9. **Filled Holey Array**: `var holey = new Array(1000); var store = holey[0];`

**Performance analysis:**

* The order of execution shows that the fastest approach is to access an empty variable directly (`var store = undefined;`), followed by accessing an object property (`var object = { value }; var store = object.value;`).
* Creating a packed array using push is slower than creating one using assign.
* Packed arrays with assign or push are faster than creating holes in a large array.
* Filling a holey array (with the first element set) is relatively fast.
* Accessing elements of an empty array with length set or last element set is slow compared to accessing it directly.

**Interpretation:**

The benchmark suggests that direct access to an undefined variable and object property access are efficient methods. Creating packed arrays using push or assign are slower, but faster than creating holes in a large array or filling one. These results can help optimize code to achieve better performance.

Please note the importance of understanding your specific use case before applying these findings to production code. This benchmark specifically targets basic operations and their relative efficiency.

Related benchmarks:

Holey, Preallocated vs Packed, Pushed 3 (version: 6)

Comparing performance of: Create holey vs Create packed (push) vs Create packed (assign) vs Read holey vs Read packed vs Read object vs Read value vs Math vs Create empty vs Create empty, set length vs Create empty, set last vs Create holey, fill

Created: 3 years ago by: Registered User

Jump to the latest result

Create holey

Create packed (push)

Create packed (assign)

Read holey

Read packed

Read object

Read value

Math

Create empty

Create empty, set length

Create empty, set last

Create holey, fill

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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