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

Historical Performance Data aggregated from 7 community runs

Desktop Results:

Chrome 7 runs

equal null

13.9M/s

typeof

13.0M/s

strict equal undefined

5.8M/s

Fastest: equal null (2.4x faster)

View exact numbers

✓ equal null: 13,932,729 ops/sec
• typeof: 13,048,696 ops/sec
• strict equal undefined: 5,826,321 ops/sec

Results show median performance across all community submissions. Run this benchmark yourself to verify on your device.

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: 2 years 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

equal null

7.3M/s

typeof

7.3M/s

strict equal undefined

3.8M/s

View exact numbers

Test name	Executions per second
✓ equal null	7,295,690 Ops/sec
typeof	7,283,049 Ops/sec
strict equal undefined	3,752,785 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 `==`).

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

Go to the latest result

typeof

strict equal undefined

equal null

Historical Performance Data aggregated from 7 community runs

Desktop Results:

Chrome 7 runs

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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

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

Go to the latest result

typeof

strict equal undefined

equal null

Historical Performance Data aggregated from 7 community runs

Desktop Results:

Chrome 7 runs

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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

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