Benchmark: undefined vs. typeof vs. in vs. hasOwnProperty

Script Preparation code:

var obj = { a: 1, b: 2, c: 3, d: 4, e: 5 };

Tests:

undefined
undefined !== obj.d;
typeof
'undefined' !== typeof obj.d;
in
'd' in obj;
hasOwnProperty
obj.hasOwnProperty( 'd' );
truthy
!! obj.d;

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
undefined
typeof
in
hasOwnProperty
truthy

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 26 days ago):

LLMs can make mistakes. Check important info.

Let's dive into the world of JavaScript microbenchmarks.

**Benchmark Definition**

The provided JSON represents a benchmark that tests the performance of different object lookup methods in JavaScript:

* `undefined !== obj.d;`
* `'undefined' !== typeof obj.d;`
* `'d' in obj;`
* `obj.hasOwnProperty('d');`
* `!! obj.d;`

These test cases aim to measure the execution time and speed of each method, which is essential for optimizing object lookup performance.

**Options Compared**

The benchmark compares five different methods for checking if a property exists or has a specific value:

1. **`undefined !== obj.d;`**: Checks if `obj.d` is not equal to `undefined`.
2. **`'undefined' !== typeof obj.d;`**: Compares the string `'undefined'` with the type of `obj.d` using the `typeof` operator.
3. **`'d' in obj;`**: Uses the `in` operator to check if property name `'d'` exists in object `obj`.
4. **`obj.hasOwnProperty('d');`**: Checks if `obj` has a property with the name `'d'` using the `hasOwnProperty` method.
5. **`!! obj.d;`**: Uses the double-bang operator (`!!`) to convert `obj.d` to a boolean value.

**Pros and Cons of Each Approach**

Here's a brief summary of each approach:

1. **`undefined !== obj.d;`**:
	* Pros: Simple, fast.
	* Cons: Can be slower for large objects due to property lookup overhead.
2. **`'undefined' !== typeof obj.d;`**:
	* Pros: Portable across different environments (including older browsers).
	* Cons: May be slower than other methods due to the type check.
3. **`'d' in obj;`**:
	* Pros: Fast and efficient for simple object lookups.
	* Cons: May not work correctly if `obj` has a property with the same name as another value (e.g., `{a: 'd', b: 2}`).
4. **`obj.hasOwnProperty('d');`**:
	* Pros: Ensures correct behavior even when dealing with inherited properties.
	* Cons: May be slower than other methods due to additional method call overhead.
5. **`!! obj.d;`**:
	* Pros: Concise and easy to read.
	* Cons: May not work correctly if `obj.d` is an empty value (e.g., `''`, `0`, `null`, etc.).

**Library and Purpose**

None of the above methods use any external libraries. They are all built-in JavaScript operators or methods.

**Special JS Features or Syntax**

The benchmark uses the following special features:

* **`typeof` operator**: Returns a string indicating the type of its operand.
* **`in` operator**: Tests if an object has a property with a given name.
* **`hasOwnProperty` method**: Checks if an object has a property with the same name as the current object.

**Other Alternatives**

If you need to optimize object lookup performance in your JavaScript code, consider using:

1. **`Object.hasOwn` method**: Similar to `hasOwnProperty`, but ensures correct behavior even when dealing with inherited properties.
2. **`Map` data structure**: Provides fast and efficient key-value storage and retrieval.
3. **`Proxy` objects**: Allow you to control property access and manipulation, which can improve performance in certain scenarios.

Keep in mind that the choice of method depends on your specific use case and requirements. MeasureThat.net provides a valuable resource for benchmarking different approaches and finding the best solution for your needs.

Latest run results:

Run details: (Test run date: 3 years ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/93.0.4577.82 Safari/537.36

Browser/OS: Chrome 93 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
undefined	6291454.0 Ops/sec
typeof	17900852.0 Ops/sec
in	17963322.0 Ops/sec
hasOwnProperty	16298412.0 Ops/sec
truthy	17771288.0 Ops/sec

Related benchmarks:

undefined vs. typeof vs. in vs. hasOwnProperty (version: 0)

Object lookup performance

Comparing performance of: undefined vs typeof vs in vs hasOwnProperty vs truthy

Created: 7 years ago by: Guest

Jump to the latest result

undefined

typeof

in

hasOwnProperty

truthy

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 26 days ago):