Benchmark: undefined vs. typeof vs. in vs. hasOwnProperty 32

Script Preparation code:

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

Tests:

undefined
if(undefined !== obj['d']){}
typeof
if('undefined' !== typeof obj['d']){}
in
if('d' in obj){}
hasOwnProperty
if(obj.hasOwnProperty( 'd' )){}
bool
if(!!obj['d']){}
Undefined2
if(obj['d']!==undefined){}
undefined3
if(obj['d']!=undefined){}
undefined4
if(obj['d']==undefined){}
bool2
if(obj['d']){}

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
undefined
typeof
in
hasOwnProperty
bool
Undefined2
undefined3
undefined4
bool2

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 25 days ago):

LLMs can make mistakes. Check important info.

Let's dive into the world of JavaScript microbenchmarks on MeasureThat.net.

**Benchmark Definition JSON**

The benchmark definition JSON provides the necessary information to run the tests. Here's what we have:

* `Name`: The name of the benchmark, which is "undefined vs. typeof vs. in vs. hasOwnProperty 32".
* `Description`: A brief description of the benchmark, which is "Object lookup performance".
* `Script Preparation Code`: A JavaScript code snippet that creates an object with properties `a`, `b`, `c`, `d`, and `e`. This code will be executed before each test.
* `Html Preparation Code`: An empty string, indicating that no HTML preparation code is required.

**Individual Test Cases**

We have 8 individual test cases, each defining a different scenario for testing object lookup performance. Here's what we need to know about each:

1. **undefined**: Tests if checking if an undefined variable is not equal to an object property.
2. **typeof**: Tests if checking if the type of an object property is not equal to `undefined`.
3. **in**: Tests if checking if a key exists in an object using the `in` operator.
4. **hasOwnProperty**: Tests if checking if an object has a specific own property using the `hasOwnProperty()` method.
5. **bool**: Tests if checking if a boolean value is not equal to `undefined`.
6. **Undefined2**, **undefined3**, and **undefined4**: These tests are variations of the previous one, with slight differences in the condition used.

**What's being tested?**

We're testing how fast JavaScript can look up properties in an object using different operators or methods. The idea is to see which approach is fastest for this particular task.

**Options compared**

The main options being compared here are:

* `in` (using the `in` operator)
* `hasOwnProperty()` (using a method)
* `===`, `!==`, and other comparison operators
* Boolean checks (`!!obj['d']`, `obj['d'] === undefined`, etc.)

**Pros and Cons**

Here's a brief summary of each option:

1. **in**: Fast, but may not be as accurate or reliable as other methods.
2. **hasOwnProperty()**: More accurate and reliable than `in`, but may be slower due to the method call.
3. **Comparison operators (`===`, `!==`)**: Quick and straightforward, but may have issues with handling `undefined` values.
4. **Boolean checks (`!!obj['d']`, etc.)**: Fast and simple, but may not account for all edge cases.

**Library**

None of these options rely on a specific library.

**Special JavaScript features or syntax**

None of the test cases use any special JavaScript features or syntax beyond what's commonly found in modern JavaScript implementations. However, some versions of `in` might have issues with handling certain types of objects (e.g., objects with undefined properties).

**Other alternatives**

If you were to modify this benchmark to test other scenarios, here are a few ideas:

* Test the performance of different data structures (e.g., arrays, sets, maps) for lookup operations.
* Experiment with different caching strategies or techniques to speed up lookups.
* Compare the performance of different browsers or versions.

These alternatives could provide more insight into JavaScript's performance capabilities and help identify potential optimization opportunities.

Latest run results:

Run details: (Test run date: 4 years ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:79.0) Gecko/20100101 Firefox/79.0

Browser/OS: Firefox 79 on Windows

View result in a separate tab

Test name	Executions per second
undefined	91090528.0 Ops/sec
typeof	219349440.0 Ops/sec
in	132360544.0 Ops/sec
hasOwnProperty	131976752.0 Ops/sec
bool	219486352.0 Ops/sec
Undefined2	95855224.0 Ops/sec
undefined3	96450120.0 Ops/sec
undefined4	96566920.0 Ops/sec
bool2	233647312.0 Ops/sec

Related benchmarks:

undefined vs. typeof vs. in vs. hasOwnProperty 32 (version: 0)

Object lookup performance

Comparing performance of: undefined vs typeof vs in vs hasOwnProperty vs bool vs Undefined2 vs undefined3 vs undefined4 vs bool2

Created: 4 years ago by: Guest

Jump to the latest result

undefined

typeof

in

hasOwnProperty

bool

Undefined2

undefined3

undefined4

bool2

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 25 days ago):