Benchmark: += vs join - MeasureThat.net

Script Preparation code:

let a = ""

Tests:

+=
let a = "" for (i = 0; i < 1000; i++) { a += i }
push
let a = "" for (i = 0; i < 1000; i++) { a.concat(i) }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
+=
push

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:125.0) Gecko/20100101 Firefox/125.0

Browser/OS: Firefox 125 on Windows

View result in a separate tab

Test name	Executions per second
+=	33424.0 Ops/sec
push	37708.1 Ops/sec

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

LLMs can make mistakes. Check important info.

Measuring JavaScript performance is crucial for developers to optimize their applications and ensure smooth user experiences.

The provided JSON represents a benchmark test case on the MeasureThat.net website, where users can create and run JavaScript microbenchmarks. The test case compares two approaches: using the `+=` operator (also known as chained assignment) versus using the `concat()` method with the `push()` method.

**What are we testing?**

We're measuring the performance difference between these two approaches:

1. `+=`: This is a shorthand for "assign and add." It's used to incrementally build up a string by appending a value to an existing string.
2. `concat() + push()`: This approach involves using the `concat()` method to concatenate strings and then pushing values onto an array.

**Options compared:**

The two options being tested are:

1. `+=` (Chained Assignment)
2. `concat()` + `push()` (Method Call Approach)

**Pros and Cons of each approach:**

**`+=` (Chained Assignment)**

Pros:

* More concise and readable code
* Can be faster for small strings or arrays, as it avoids the overhead of method calls
* Native JavaScript optimization can optimize this approach

Cons:

* May lead to performance issues if used with large strings or arrays
* Can cause memory fragmentation due to frequent string allocations
* Less control over the string building process compared to `concat()` + `push()`

**`concat()` + `push()` (Method Call Approach)**

Pros:

* More explicit and controllable way of string concatenation and array manipulation
* Avoids memory fragmentation issues associated with `+=`
* Can be more efficient for large strings or arrays, as it allows the browser to optimize the allocation process

Cons:

* Less concise and less readable code compared to `+=`
* May have overhead due to method calls
* Requires manual management of the array and string concatenation

**Library and special JS feature:**

There is no specific library mentioned in this test case. However, some browsers (like Chrome) use a technique called "string pooling" to optimize string manipulation. This involves allocating a pool of strings that can be reused throughout the application.

**Special JS feature:**

There is a notable difference between these two approaches - the way they handle caching and string allocation. The `+=` operator uses a technique called " incremental string building," which avoids creating temporary strings on each iteration, reducing memory allocation overhead.

**Alternatives:**

Other alternatives for string concatenation in JavaScript include:

* Using a template engine like Handlebars or Mustache
* Utilizing a dedicated library like Underscore.js or Lodash for string manipulation and array operations
* Leveraging modern JavaScript features like `String.prototype.repeat()` (introduced in ECMAScript 2015) for efficient string repetition

Keep in mind that the best approach depends on your specific use case, performance requirements, and coding style preferences.

Related benchmarks:

+= vs join (version: 0)

Comparing performance of: += vs push

Created: 2 years ago by: Guest

Jump to the latest result

+=

push

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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