Benchmark: Compare typeof vs null check 2

Script Preparation code:

const value = null

Tests:

Is number
const value = null return typeof value === 'string'
Is null
const value = null return value == null

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Is number
Is null

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Linux; Android 10; K) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/126.0.0.0 Mobile Safari/537.36

Browser/OS: Chrome Mobile 126 on Android

View result in a separate tab

Test name	Executions per second
Is number	17957674.0 Ops/sec
Is null	16449643.0 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 benchmark and explain what's being tested.

**Benchmark Overview**

The benchmark is designed to compare two approaches for checking if a variable is `null` or not in JavaScript:

1. Using the `typeof` operator with a string comparison (`typeof value === 'string'`)
2. Using the `==` (double equals) operator for a loose equality check (`value == null`)

**Options Compared**

The benchmark compares two options for checking if a variable is `null` or not:

Option 1: `typeof value === 'string'`

This approach uses the `typeof` operator to get the type of the variable, and then checks if it's equal to `'string'`. This will return true for any object that has a `toString()` method, including non-string values. This is because `typeof` returns one of six strings (`"number"`, `"object"`, `"boolean"`, `"function"`, `"string"`, or `"undefined"`), and the comparison with `'string'` will match any value that's not `null`.

Option 2: `value == null`

This approach uses a loose equality check using the `==` operator. This will return true only if the variable is exactly equal to the value `null`. If the variable is an object or a non-numeric value, this comparison will be false.

**Pros and Cons of Each Approach**

Option 1: `typeof value === 'string'`

Pros:

* More robust for checking non-string values (e.g., objects, functions)
* Less prone to typos or unexpected behavior

Cons:

* May return true for non-`null` values that have a `toString()` method
* Can be slower due to the additional step of getting the type

Option 2: `value == null`

Pros:

* Faster and more lightweight compared to Option 1
* Returns true only when the variable is exactly equal to `null`

Cons:

* May return false for non-`null` values (e.g., objects, functions)
* Prone to typos or unexpected behavior if not used carefully

**Library Usage**

In this benchmark, no library is explicitly mentioned. However, it's worth noting that the use of `typeof` relies on the JavaScript engine's implementation of the `toString()` method.

**Special JS Features/Syntax**

There are no special JS features or syntax mentioned in this benchmark.

**Other Alternatives**

Alternative approaches for checking if a variable is `null` or not include:

1. Using the `===` operator with an explicit comparison to `null` (`value === null`)
2. Using the `instanceof` operator, which can be used to check if an object is an instance of a specific constructor (e.g., `value instanceof Null`)

However, these alternatives are not part of this benchmark, and their performance may vary depending on the JavaScript engine and browser.

Overall, the benchmark provides a useful comparison between two common approaches for checking if a variable is `null` or not in JavaScript.

Related benchmarks:

Compare typeof vs null check 2 (version: 0)

Comparing performance of: Is number vs Is null

Created: 2 years ago by: Guest

Jump to the latest result

Is number

Is null

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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