Benchmark: falsy vs typeof - MeasureThat.net

Script Preparation code:

let a = null
let b = null

Tests:

falsy
let a = undefined let b = null if (a) console.log('-') if (b) console.log('-')
typeof
let a = undefined let b = null if (typeof a === 'undefined') console.log('-') if (typeof b === 'undefined') console.log('-')

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
falsy
typeof

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/134.0.0.0 Safari/537.36

Browser/OS: Chrome 134 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
falsy	103260400.0 Ops/sec
typeof	248565.4 Ops/sec

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

LLMs can make mistakes. Check important info.

I'll break down the provided benchmark and explain what's being tested, compared, and other considerations.

**Benchmark Overview**

The test compares two different approaches to handle falsy values in JavaScript. Falsy values are values that evaluate to `false` in a boolean context.

**Test Case 1: "falsy"**

In this test case, the script checks if `a` or `b` is falsy using an `if` statement:
```javascript
let a = null;
let b = null;

if (a) console.log('-');
if (b) console.log('-');
```
The script will execute the `console.log()` statements because both `a` and `b` are considered falsy values.

**Pros and Cons**

* Pros: Simple and straightforward approach.
* Cons: This approach can lead to unexpected behavior if not handled carefully, as falsy values can cause issues in certain contexts (e.g., array methods).

**Test Case 2: "typeof"**

In this test case, the script uses the `typeof` operator to check if `a` or `b` is undefined:
```javascript
let a = undefined;
let b = null;

if (typeof a === 'undefined') console.log('-');
if (typeof b === 'undefined') console.log('-');
```
The `typeof` operator returns `'undefined'` for both `a` and `b`, so the script will not execute the `console.log()` statements.

**Pros and Cons**

* Pros: More explicit and safer way to check if a value is undefined.
* Cons: May be slower due to the use of `typeof`.

**Library Used**

In this benchmark, no specific JavaScript library is used. However, the use of `console` suggests that the test is running in a browser environment with a console API.

**Other Considerations**

Both approaches have their trade-offs:

* Using an `if` statement and checking for falsy values can lead to issues if not handled carefully.
* Using the `typeof` operator provides more explicit and safer checks, but may be slower due to its overhead.

**Alternatives**

If you're looking for alternative ways to handle falsy values in JavaScript, here are a few options:

1. **Using the nullish coalescing operator (`??`)**: Introduced in ES2020, this operator returns the first operand if it's not null or undefined; otherwise, it returns the second operand.
2. **Using a custom function**: You can create a custom function that checks for falsy values and provides more control over the behavior.

Here's an example of using the nullish coalescing operator:
```javascript
let a = null;
let b = null;

let result = a ?? b;

console.log(result); // Output: null
```
Keep in mind that these alternatives may have their own pros and cons, depending on your specific use case.

Related benchmarks:

falsy vs typeof (version: 0)

Comparing performance of: falsy vs typeof

Created: 6 years ago by: Guest

Jump to the latest result

falsy

typeof

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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