Toggle navigation
MeasureThat.net
Create a benchmark
Tools
Feedback
FAQ
Register
Log In
undefined vs. typeof vs. in vs. hasOwnProperty vs bool
(version: 0)
Object lookup performance
Comparing performance of:
undefined vs typeof vs in vs hasOwnProperty vs bool
Created:
6 years ago
by:
Registered User
Jump to the latest result
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' );
bool
obj.d;
Rendered benchmark preparation results:
Suite status:
<idle, ready to run>
Run tests (5)
Previous results
Fork
Test case name
Result
undefined
typeof
in
hasOwnProperty
bool
Fastest:
N/A
Slowest:
N/A
Latest run results:
No previous run results
This benchmark does not have any results yet. Be the first one
to run it!
Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
**Benchmark Overview** The provided JSON represents a JavaScript microbenchmarking test case, specifically designed to measure the performance of different object lookup methods in JavaScript. **Object Lookup Methods Compared** The benchmark compares five different object lookup methods: 1. **`undefined`**: Directly accessing an undefined property on an object. 2. **`typeof`**: Using the `typeof` operator to check the type of a variable or expression, including object properties. 3. **`in`**: Using the `in` operator to test if a property is present in an object. 4. **`hasOwnProperty`**: Using the `hasOwnProperty` method on an object to check if it has a specific property. 5. **`bool`** (not explicitly defined in the code, but likely referring to a boolean literal or comparison): Directly accessing a boolean value. Each test case measures the performance of one of these methods when applied to the same property (`obj.d`) on an object `obj`. **Pros and Cons of Each Approach** 1. **`undefined`**: This approach can be fast since it directly accesses the memory location of the property, but it's also prone to errors if not used carefully. 2. **`typeof`**: Using `typeof` can provide more information about the type of property being accessed, but it may incur a small performance overhead due to the operator's execution cost. 3. **`in`**: The `in` operator is generally fast and straightforward, making it a popular choice for object lookup. However, it might not work as expected if the property name is in a non-string format (e.g., numeric). 4. **`hasOwnProperty`**: This method checks if the object has the property as its own property, rather than inheriting it from a prototype chain. While it provides more accurate results, it may be slower due to the additional lookup. 5. **`bool`** (assuming a boolean literal or comparison): Directly accessing a boolean value is likely to be very fast, but it's not applicable in this case since `obj.d` doesn't evaluate to a boolean. **Library and Purpose** In this benchmark, none of the libraries are explicitly used. However, it's worth noting that some JavaScript engines may use internal libraries or optimizations for object lookup, which could potentially affect the results of this benchmark. **Special JS Features and Syntax** None of the individual test cases appear to exploit any special JavaScript features or syntax, except possibly for the `typeof` operator, which is a built-in operator in JavaScript. However, its usage is straightforward enough that it's not worth highlighting as a unique aspect of these tests. **Other Alternatives** Some alternative object lookup methods could be explored in future benchmarks, such as: * Using `in` with a non-string property name (e.g., a numeric index) * Employing custom getter or setter functions to manipulate property access * Utilizing `Object.prototype.hasOwnProperty.call()` or other similar methods * Testing the performance of different object types (e.g., objects, arrays) or data structures
Related benchmarks:
undefined vs. typeof vs. in vs. hasOwnProperty
undefined vs. hasOwnProperty
undefined vs. typeof vs. in vs. hasOwnProperty 2
undefined vs. typeof vs. in vs. hasOwnProperty big object
undefined vs. typeof vs. in vs. hasOwnProperty for non-existing property
Comments
Confirm delete:
Do you really want to delete benchmark?