Benchmark: undefined vs. typeof vs. in vs. hasOwnProperty 6

Script Preparation code:

var obj = { a: 1, b: 2, c: 3, d: 4, e: 5 };
var undef = undefined;
function a() {undef !== obj.d}
function b() {undefined !== obj.d}
function c() {'d' in obj}
function d() {!!obj.d}
function e() {'undefined' !== typeof obj.d;}
function f() {obj.hasOwnProperty( 'd' );}

Tests:

a
a()
b
b()
c
c()
d
d()
e
e()
f
f()

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
a
b
c
d
e
f

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/84.0.4147.125 Safari/537.36 Edg/84.0.522.59

Browser/OS: Chrome 84 on Windows

View result in a separate tab

Test name	Executions per second
a	3268233.0 Ops/sec
b	2630620.5 Ops/sec
c	4845471.5 Ops/sec
d	4981019.5 Ops/sec
e	4950541.5 Ops/sec
f	4575771.5 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's dive into the explanation of the provided benchmark.

**Benchmark Definition**

The benchmark is designed to compare the performance of four different methods for checking if a property exists in an object: `undefined vs. typeof`, `in`, and `hasOwnProperty`. The benchmark also includes two additional functions, `d()` and `e()`, which use these operators to check if a property exists.

**Script Preparation Code**

The script preparation code defines a sample object `obj` with properties `a` through `e`, as well as several function definitions:

* `a()`: checks if `undef` is not equal to `obj.d`
* `b()`: checks if `undefined` is not equal to `obj.d`
* `c()`: uses the `in` operator to check if `'d'` exists in `obj`
* `d()`: uses the `!!` operator (a doublebang) to convert `obj.d` to a boolean value
* `e()`: checks if `'undefined'` is not equal to the result of `typeof obj.d`
* `f()`: uses the `hasOwnProperty()` method to check if `obj` has a property named `'d'`

**Individual Test Cases**

The benchmark consists of six test cases, each corresponding to one of the function definitions:

1. `a()`
2. `b()`
3. `c()`
4. `d()`
5. `e()`
6. `f()`

Each test case is designed to measure the performance of a specific operator or method.

**Options Compared**

The benchmark compares four different methods for checking if a property exists in an object:

1. `undefined vs. typeof`: This comparison checks how the JavaScript engine handles checks involving `undefined` and `typeof`.
2. `in`: This comparison measures the performance of using the `in` operator to check for property existence.
3. `hasOwnProperty()`: This comparison uses the `hasOwnProperty()` method, which is a specific method for checking if an object has a given property.

**Pros and Cons**

Here are some pros and cons of each approach:

* **`undefined vs. typeof`**: Pros: Simple to implement, easy to understand. Cons: Can be slower than other methods due to the overhead of comparing `undefined` with other values.
* **`in`**: Pros: Fast, efficient. Cons: May not work correctly in all cases (e.g., when using a custom object prototype).
* **`hasOwnProperty()`**: Pros: Specific, targeted method for checking property existence on an object's own properties. Cons: May be slower than the `in` operator due to its additional overhead.

**Library and Special JS Feature**

There are no libraries or special JavaScript features used in this benchmark. However, it does utilize some advanced syntax features, such as:

* The `!!` operator (doublebang)
* The use of template literals (`'d' in obj`)

These features are specific to modern JavaScript and are not essential for understanding the basic mechanics of the benchmark.

**Other Alternatives**

If you're interested in exploring alternative methods or variations on this benchmark, here are some ideas:

1. Compare different ways of checking property existence using `Object.prototype.hasOwnProperty()` instead of `hasOwnProperty()`.
2. Add a new test case that uses a custom object prototype to demonstrate how the `in` operator works.
3. Modify the script preparation code to use more complex or edge-case properties, such as nested objects or arrays.

Feel free to experiment and modify the benchmark to suit your interests!

Related benchmarks:

undefined vs. typeof vs. in vs. hasOwnProperty 6 (version: 0)

Object lookup performance

Comparing performance of: a vs b vs c vs d vs e vs f

Created: 4 years ago by: Guest

Jump to the latest result

a

b

c

d

e

f

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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