Benchmark: String slice vs. array sliceee

Tests:

String concat
var arr = new Map() let prev="" for (let i = 0;i<1000;++i){ prev+="ABC:"; arr.set(+i,prev); } function process(s){ return s.slice(0,s.lastIndexOf(':')) } for (const [key,value] of arr){ let s = process(arr.get(key)) while(s.length){ s = process(s) } arr.delete(key) }
Array spread
var arr = new Map() let prev=[] for (let i = 0;i<1000;++i){ prev =[...prev, 'ABC'] arr.set(+i,prev); } function process(s){ return s.slice(0,s.length-1) } for (const [key,value] of arr){ let s = process(arr.get(key)) while(s.length){ s = process(s) } arr.delete(key) }
Array with concat
var arr = new Map() let prev=[] for (let i = 0;i<1000;++i){ prev = prev.concat('ABC') arr.set(+i,prev); } function process(s){ return s.slice(0,s.length-1) } for (const [key,value] of arr){ let s = process(arr.get(key)) while(s.length){ s = process(s) } arr.delete(key) }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
String concat
Array spread
Array with concat

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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I'll break down the benchmark and explain what's being tested, compared, and some pros and cons of each approach.

**Benchmark Overview**

The benchmark compares three ways to concatenate strings (or simulate string concatenation) in JavaScript:

1. **String slice**: Using `slice()` method with a substring of the original string.
2. **Array spread**: Using the spread operator (`...`) to create a new array from an existing one.
3. **Array with concat**: Using the `concat()` method to concatenate arrays.

**Test Cases**

Each test case has two parts:

1. A benchmark definition: This is a JavaScript function that simulates the concatenation process, which includes:
	* Creating an array of strings (or a map with string values).
	* Repeating a loop to populate the array (or map) with the same string.
	* Defining a `process()` function that takes a string as input and returns a modified version of it (in this case, by removing characters from the end of the string).
2. A test name: This is a descriptive name for the benchmark.

**Comparison**

The comparison between these three approaches will likely measure:

1. **Performance**: How fast each approach executes the concatenation process.
2. **Memory usage**: The amount of memory used by each approach during execution.

**Pros and Cons**

Here are some pros and cons of each approach:

### String Slice

Pros:

* Simple to implement
* Can be efficient if the substring is small

Cons:

* May create a new string object, which can lead to increased memory usage.
* Can be slower for large substrings or repeated concatenations.

### Array Spread

Pros:

* Creates a new array, which can help avoid modifying the original data.
* Can be faster than other approaches because it avoids creating intermediate strings.

Cons:

* Requires JavaScript 7+ support (older browsers may not support the spread operator).
* May create unnecessary temporary objects during execution.

### Array with Concat

Pros:

* Avoids creating intermediate string objects, which can help reduce memory usage.
* Can be slower due to the overhead of concatenating arrays.

Cons:

* May require additional memory allocation for the new array.
* Can lead to increased garbage collection frequency.

**Library and Special JS Features**

None of the test cases use any libraries or special JavaScript features beyond what's already described.

Related benchmarks:

String slice vs. array sliceee (version: 0)

Comparing performance of: String concat vs Array spread vs Array with concat

Created: 2 years ago by: Guest

Jump to the latest result

String concat

Array spread

Array with concat

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):