Benchmark: Javascript 'concat()' vs '+' for strings

Script Preparation code:

var string1 = "Hello ";
var string2 = " world!";

Tests:

concat()
for(i = 0; i < 1000; i++) { string1.concat(string2); }
plus_operator
for(i = 0; i < 1000; i++) { string1 + string2; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
concat()
plus_operator

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/132.0.0.0 Safari/537.36

Browser/OS: Chrome 132 on Windows

View result in a separate tab

Test name	Executions per second
concat()	43584.9 Ops/sec
plus_operator	47679.7 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark and explain what's being tested, the options compared, their pros and cons, and other considerations.

**Benchmark Definition**

The benchmark is designed to measure the performance difference between two approaches for concatenating strings in JavaScript: using the `concat()` method and using the `+` operator.

**Script Preparation Code**

The script preparation code defines two string variables, `string1` and `string2`, which are assigned the values `"Hello "` and `" world!"` respectively. This sets up a constant string concatenation scenario where both approaches will be tested.

**Options Compared**

There are two options being compared:

1. **concat() method**: The `concat()` method is used to concatenate strings by calling it with two arguments, effectively returning a new string that is the combination of the two input strings.
2. **+ operator**: The `+` operator is used for string concatenation, which combines two strings into a single string by concatenating their characters.

**Pros and Cons**

* **concat() method:**
	+ Pros:
		- More explicit and readable way to concatenate strings
		- Less prone to errors due to its more predictable behavior
	+ Cons:
		- May be slower than the `+` operator for very large strings
		- Requires an additional function call, which can incur overhead
* **+ operator:**
	+ Pros:
		- Often faster and more efficient for small to medium-sized string concatenations
		- Simplifies code by eliminating the need for a separate `concat()` method call
	+ Cons:
		- Can lead to errors if not used carefully (e.g., with null or undefined values)
		- May be less readable for some developers due to its implicit behavior

**Library and Special Features**

The benchmark does not use any specific JavaScript libraries, but it does utilize the `String` object's concatenation methods.

There are no special JavaScript features or syntax used in this benchmark.

**Other Considerations**

When evaluating the performance of string concatenation approaches, other factors to consider include:

* The size and complexity of the strings being concatenated
* The presence of other operations that may impact performance (e.g., loops, conditionals)
* The specific browser or environment being tested

In general, for small to medium-sized string concatenations, the `+` operator is often a good choice due to its simplicity and efficiency. However, when working with very large strings or in situations where readability and explicitness are crucial, the `concat()` method may be a better option.

**Alternatives**

If you're interested in exploring other string concatenation approaches or alternatives, some options include:

* Using template literals (introduced in ECMAScript 2015)
* Utilizing libraries like Lodash's `string union` function
* Employing more advanced techniques, such as using a buffer-based approach or leveraging WebAssembly for optimized performance

Related benchmarks:

Javascript 'concat()' vs '+' for strings (version: 0)

Testing the performance difference between concat() and the + operator for strings in javascript

Comparing performance of: concat() vs plus_operator

Created: 9 years ago by: Guest

Jump to the latest result

concat()

plus_operator

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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