Benchmark: Array.from vs Spread for strings

Script Preparation code:

var str = '';
for(var i=0;i<100;i++) {
  str += 'a';
}

Tests:

Array.from
var other = Array.from(str);
Spread
var other = [...str];

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Array.from
Spread

Fastest: N/A

Slowest: N/A

Latest run results:

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

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Let's break down the benchmark and analyze what's being tested, along with its pros and cons.

**Benchmark Definition**

The benchmark is comparing two approaches for creating an array from a string:

1. `Array.from(str)`
2. `var other = [...str];`

**What are we testing?**

We're testing how fast these two approaches are in executing the following code snippet:
```javascript
for (var i = 0; i < 100; i++) {
  str += 'a';
}
```
This code creates a string `str` by concatenating the character `'a'` 100 times.

**Options Compared**

The two options being compared are:

1. `Array.from(str)`
2. `var other = [...str];`

**Pros and Cons of Each Approach:**

1. **`Array.from(str)`**
	* Pros:
		+ More concise and expressive, as it clearly conveys the intention of creating an array from a string.
		+ Can be more readable for developers who are familiar with this syntax.
	* Cons:
		+ May have performance overhead due to the creation of an intermediate array.
2. **`var other = [...str];` (Spread Syntax)**
	* Pros:
		+ Can take advantage of the faster spread operator (`...`) which is often optimized by modern JavaScript engines.
		+ May be faster in modern browsers that have a dedicated spread operator implementation.
	* Cons:
		+ May require more time for some developers to understand and implement, as it's not as immediately clear as `Array.from`.
		+ Can lead to more verbose code when used with other array methods.

**Library/Features Used**

None are explicitly mentioned in this benchmark definition.

**Special JS Feature/Syntax**

The spread syntax (`...`) is a relatively new feature introduced in ECMAScript 2015 (ES6). It allows for the creation of arrays from iterables, such as strings or objects. The browser results indicate that Firefox 82 has a dedicated implementation of the spread operator, which might contribute to its better performance.

**Other Alternatives**

If you want to test other approaches to creating an array from a string, here are some alternatives:

1. `str.split('')`: This method creates an array by splitting the string into individual characters using the empty string as the separator.
2. `Array.prototype.slice.call(str)`: This approach converts the string to an array using `slice()` and then calls `call()` to apply the function context.

Keep in mind that each of these alternatives may have different performance characteristics compared to `Array.from` or the spread syntax.

Related benchmarks:

Array.from vs Spread for strings (version: 0)

Comparing performance of: Array.from vs Spread

Created: 5 years ago by: Guest

Jump to the latest result

Array.from

Spread

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

No previous run results

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