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)
}

​x
 
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)
}

 
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)
}

 
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

Experimental features:

Memory measurements supported only in Chrome.
For precise memory measurements Chrome must be launched with --enable-precise-memory-info flag.
More information: Monitoring JavaScript Memory

Test case name	Result
String concat
Array spread
Array with concat

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/109.0.0.0 Safari/537.36

Browser/OS: Chrome 109 on Windows

View result in a separate tab

Test name	Executions per second
String concat	37.3 Ops/sec
Array spread	18.4 Ops/sec
Array with concat	17.7 Ops/sec

Autogenerated LLM Summary (model llama3.2:3b, generated 6 months ago):

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:

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

Test Cases

Each test case has two parts:

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).
A test name: This is a descriptive name for the benchmark.

Comparison

The comparison between these three approaches will likely measure:

Performance: How fast each approach executes the concatenation process.
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.

LLMs can make mistakes. Check important info.

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: one year ago by: Guest

Jump to the latest result

String concat

Array spread

Array with concat

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 6 months ago):

String Slice

Array Spread

Array with Concat