Benchmark: Array isArray vs typeof with string

Script Preparation code:

var test = "hello";
var test2 = ['h','e','l','l','o']
var c;

Tests:

typeof
if (typeof test === 'string') { c++; } if (typeof test2 === 'string') { c++; }
isArray
if (Array.isArray(test)) { c++; } if (Array.isArray(test2)) { c++; }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
typeof
isArray

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/130.0.0.0 Safari/537.36

Browser/OS: Chrome 130 on Windows

View result in a separate tab

Test name	Executions per second
typeof	2535554.5 Ops/sec
isArray	1446964.1 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 JSON data and explain what is being tested.

**Benchmark Definition**

The benchmark is designed to compare the performance of two approaches: using `typeof` with strings versus using the `Array.isArray()` method for detecting whether an expression evaluates to an array or a single string. The goal is to determine which approach is faster.

**Options Compared**

Two options are compared:

1. **`typeof` with strings**: This approach uses the `typeof` operator to check if a variable is a string. If it is, the increment counter `c` is incremented.
2. **`Array.isArray()` method**: This approach uses the `Array.isArray()` method to check if an expression evaluates to an array or a single string.

**Pros and Cons**

1. **`typeof` with strings**:
	* Pros: Simple and widely supported, as it's a built-in operator in JavaScript.
	* Cons: Can be slower for large arrays due to the overhead of checking the type, and may not work correctly for all types (e.g., `null`, `undefined`, etc.).
2. **`Array.isArray()` method**:
	* Pros: Optimized for performance on modern browsers and engines, and works correctly for arrays and single strings.
	* Cons: Less widely supported, as it's a more recent addition to the JavaScript standard library.

**Library and Purpose**

The `Array.isArray()` method is a built-in function in JavaScript that returns `true` if its argument evaluates to an array-like object (including arrays, objects with array-like properties, etc.). Its purpose is to provide a convenient way to check whether a variable is an array or has array-like properties.

**Special JS Feature or Syntax**

There is no special feature or syntax used in this benchmark. The code is straightforward and uses standard JavaScript constructs.

**Other Alternatives**

Alternative approaches could include:

1. **Using `instanceof`**: This approach would use the `instanceof` operator to check if a variable is an instance of the `Array` constructor. While similar to `Array.isArray()`, this method may not work correctly for all types (e.g., arrays with non-array-like properties).
2. **Using a regular expression**: A regular expression could be used to match the string pattern, but this approach would likely be slower than using `typeof` or `Array.isArray()`.

Overall, the benchmark provides a useful comparison of two performance-critical operations in JavaScript, and its results can help developers make informed decisions when working with arrays and strings in their code.

Related benchmarks:

Array isArray vs typeof with string (version: 0)

Is typeof or isArray faster for detecting if something is an array or strings or a single string

Comparing performance of: typeof vs isArray

Created: 2 years ago by: Guest

Jump to the latest result

typeof

isArray

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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