Benchmark: typeof undefined vs strict equal vs equal

Tests:

typeof
var foo = undefined; typeof foo === "undefined";
strict equal undefined
var foo = undefined; foo === undefined
equal null
var foo = undefined; foo == null

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
typeof
strict equal undefined
equal null

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/124.0.0.0 Safari/537.36 OPR/110.0.0.0

Browser/OS: Opera 110 on Windows

View result in a separate tab

Test name	Executions per second
typeof	7283049.0 Ops/sec
strict equal undefined	3752785.2 Ops/sec
equal null	7295689.5 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 three different ways to check if a variable has a value of `undefined` or `null`. The variables are initialized with `undefined` using the `var foo = undefined;` statement. There are two additional checks:

1. `typeof foo === "undefined"`: This uses the `typeof` operator to check the type of the variable.
2. `foo === undefined`: This uses a loose equality check (`===`) to compare the value of `foo` with `undefined`.
3. `foo == null`: This uses another loose equality check (`==`) to compare the value of `foo` with `null`.

**Options Compared**

The benchmark is comparing the performance of these three different approaches:

1. **typeof foo === "undefined"`: This approach uses the `typeof` operator, which returns a string indicating the type of the variable.
2. **foo === undefined`: This approach uses a loose equality check to compare the value of `foo` with `undefined`.
3. **foo == null`: This approach uses another loose equality check to compare the value of `foo` with `null`.

**Pros and Cons**

Here are some pros and cons for each approach:

1. **typeof foo === "undefined"`:
	* Pros: This approach is more strict and accurate, as it checks the type of the variable.
	* Cons: The `typeof` operator can be slower due to its additional processing.
2. **foo === undefined**:
	* Pros: This approach is faster and more straightforward, as it only compares the value of `foo` with `undefined`.
	* Cons: It's less strict than the first approach, which may lead to incorrect results if `foo` has a different type but still has the same value.
3. **foo == null**:
	* Pros: This approach is also faster and more straightforward, as it only compares the value of `foo` with `null`.
	* Cons: Like the second approach, it's less strict than the first approach and may lead to incorrect results if `foo` has a different type but still has the same value.

**Library and Special JS Features**

There are no libraries used in this benchmark. However, it's worth noting that the `typeof` operator is a built-in JavaScript operator that provides more information about the type of a variable than the loose equality checks (`===` and `==`).

Related benchmarks:

typeof undefined vs strict equal vs equal (version: 0)

Comparing performance of: typeof vs strict equal undefined vs equal null

Created: 5 years ago by: Guest

Jump to the latest result

typeof

strict equal undefined

equal null

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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