Benchmark: str += vs join - MeasureThat.net

Tests:

str array
var str =["hallo"]; str.push("world"); str.join("")
str string
var str ="hallo"; str += " world";

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
str array
str string

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/147.0.0.0 Safari/537.36 Edg/147.0.0.0

Browser/OS: Chrome 147 on Windows

View result in a separate tab

Test name	Executions per second
str array	20329484.0 Ops/sec
str string	159669792.0 Ops/sec

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

LLMs can make mistakes. Check important info.

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

**Benchmark Overview**

The MeasureThat.net benchmark tests two different ways to concatenate strings in JavaScript: using the `+=` operator and using the `join()` method.

**Test Cases**

There are two test cases:

1. **"str array"`**: This test case creates an array called `str` and pushes a string "world" onto it. It then calls the `join()` method on the array to concatenate all its elements into a single string.
2. **"str string"`**: This test case assigns a string "hallo" directly to the variable `str`. It then uses the `+=` operator to append another string " world" to the existing value of `str`.

**Comparison**

The benchmark compares the performance of these two approaches:

* Using the `+=` operator to concatenate strings
* Using the `join()` method to concatenate an array of strings

**Pros and Cons of Each Approach**

### **+= Operator**

Pros:

* Simple and straightforward way to concatenate strings
* Fast and efficient for small to medium-sized strings

Cons:

* Creates a new string object in memory on each iteration, leading to increased memory usage
* Can be slower than other methods for large strings due to the creation of intermediate objects
* Does not handle edge cases such as null or undefined values well

### **join() Method**

Pros:

* Efficient and fast way to concatenate arrays of strings
* Handles edge cases such as null or undefined values by ignoring them
* Can be faster than `+=` for large strings due to the use of a single buffer

Cons:

* Requires an array of strings, which may not always be convenient or necessary
* May have performance overhead due to the creation and manipulation of the internal buffers used by the `join()` method

**Other Considerations**

Both approaches can be affected by various factors such as:

* The size and complexity of the string being concatenated
* The type and number of intermediate objects created during concatenation
* The specific JavaScript engine and browser being used, which may optimize or implement `+=` differently than others.

**Library Used**

None of the benchmark test cases explicitly use any third-party libraries. However, it's worth noting that some browsers' built-in string manipulation functions may be implemented using external libraries or optimized with additional compiler optimizations.

**Special JavaScript Features/Syntax**

There are no special JavaScript features or syntax used in these test cases beyond standard ECMAScript syntax and the `+=` operator.

**Alternatives**

If you need to benchmark other ways of concatenating strings, you might consider testing:

* Using template literals (e.g., `${expression}`) for string interpolation
* Utilizing the `String.prototype.concat()` method or the `+` operator with multiple arguments
* Investigating the performance of concatenating strings using arrays or buffers

Related benchmarks:

str += vs join (version: 0)

simple test of concat strings

Comparing performance of: str array vs str string

Created: 5 years ago by: Guest

Jump to the latest result

str array

str string

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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