Benchmark: .toString() concatenation vs array join with compiledFunc

Script Preparation code:

var array = [{a:"asd",b:5,c:null,d:new Date()},{a:"bcd",b:6,c:void 0,d:new Date()},{a:"efg",b:8,c:-1,d:new Date()}]
var compiledFuncConcat = new Function("data", "return String((data&&data.a))+String((data&&data.b))+String((data&&data.c))+String((data&&data.d));");
var compiledFuncJoin = new Function("data", "return [(data&&data.a),(data&&data.b),(data&&data.c),(data&&data.d)].join('');");

Tests:

String concat
var resultArr=[]; for(let i=0, ii = 10000; i<ii; i++){ resultArr.push(compiledFuncConcat(array[i%array.length])) }
String join
var resultArr=[]; for(let i=0, ii = 10000; i<ii; i++){ resultArr.push(compiledFuncJoin(array[i%array.length])); }
string join directly
var resultArr=[]; for(let i=0, ii = 10000; i<ii; i++){ let data = array[i%array.length]; resultArr.push([(data&&data.a),(data&&data.b),(data&&data.c),(data&&data.d)].join('')); }
String concat directly
var resultArr=[]; for(let i=0, ii = 10000; i<ii; i++){ let data = array[i%array.length]; resultArr.push(String((data&&data.a))+String((data&&data.b))+String((data&&data.c))+String((data&&data.d))); }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
String concat
String join
string join directly
String concat directly

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: one year ago)

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Browser/OS: Firefox 102 on Windows

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Test name	Executions per second
String concat	58.4 Ops/sec
String join	35.3 Ops/sec
string join directly	34.5 Ops/sec
String concat directly	59.2 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down the benchmark and explain what's being tested.

**What is being tested?**

The benchmark tests three different approaches to concatenate strings in JavaScript:

1. **String concatenation**: This approach uses the `+` operator to concatenate strings together.
2. **Array join with compiled function**: This approach uses the `join()` method on an array of strings, where a compiled function is used to extract and concatenate individual string elements from each object in the array.
3. **Direct string concatenation without joining**: This approach also uses the `+` operator to concatenate strings together, but this time without using any intermediate data structure like an array.

**Options comparison**

The three approaches have different performance characteristics:

* **String concatenation**: This is a simple and straightforward approach that works well for small strings. However, it can be slow for large strings because the `+` operator creates a new string object each time.
* **Array join with compiled function**: This approach uses a compiled function to extract and concatenate individual string elements from each object in the array. The compiled function is created once before running the benchmark, which reduces overhead compared to creating a new function on each iteration. However, this approach may incur additional overhead due to the creation of the compiled function.
* **Direct string concatenation without joining**: This approach avoids the overhead of the `join()` method and creates strings incrementally using the `+` operator.

**Pros and cons**

Here are some pros and cons for each approach:

* **String concatenation**:
	+ Pros: Simple, easy to understand, works well for small strings.
	+ Cons: Slow for large strings due to string object creation on each iteration.
* **Array join with compiled function**:
	+ Pros: Reduces overhead by creating a single compiled function, can be faster than direct concatenation for large arrays.
	+ Cons: May incur additional overhead due to the creation of the compiled function, requires more memory to store the array and compiled function.
* **Direct string concatenation without joining**:
	+ Pros: Avoids the overhead of the `join()` method, creates strings incrementally using the `+` operator, which can be faster than direct concatenation for large strings.
	+ Cons: Requires manual management of string creation, may not be as readable or maintainable as other approaches.

**Library and syntax**

The benchmark uses a custom compiled function to extract and concatenate individual string elements from each object in the array. This is done using the `new Function()` constructor, which creates a new function on the fly based on the provided code.

The test cases also use the `&&` operator to check if a property exists on an object before trying to access it. This is a common JavaScript idiom for avoiding null pointer exceptions.

**Other considerations**

When writing benchmarks, it's essential to consider factors such as:

* **Sampling**: How representative are the benchmark results of the overall performance?
* **Noise reduction**: Are there any noise sources that can skew the benchmark results?
* **Consistency**: Are the benchmark results consistent across different hardware and software configurations?

In this case, the benchmark seems well-designed, but it's essential to review the raw benchmark data and consider potential issues like:

* **Sampling bias**: Is the sample size representative of the target audience?
* **Noise reduction**: Are there any factors that could skew the benchmark results, such as caching or other optimizations?

**Alternatives**

Some alternative approaches for string concatenation in JavaScript include:

* Using a library like Lodash or Underscore.js, which provides optimized functions for common tasks like string concatenation.
* Using template literals (introduced in ECMAScript 2015), which provide a more concise and readable way to concatenate strings.
* Using a string interpolation library like Interpolate.js.

However, these alternatives may not be as effective as the custom compiled function approach used in this benchmark for extremely large arrays or performance-critical applications.

Related benchmarks:

.toString() concatenation vs array join with compiledFunc (version: 0)

Comparing performance of: String concat vs String join vs string join directly vs String concat directly

Created: one year ago by: Guest

Jump to the latest result

String concat

String join

string join directly

String concat directly

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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