Benchmark: Determining if a variable is an object

Determining if a variable is an object (version: 1)

Compares three ways of determining if a variable is an object. - Check if object by comparing value to an object instantiated from the value - Using typeof - Using instanceof

Comparing performance of: Check if object by comparing value to an object instantiated from the value - passing in an object vs Check if object by comparing value to an object instantiated from the value - passing in a string vs Check if object by comparing value to an object instantiated from the value - passing in a string object vs Check if object by comparing value to an object instantiated from the value - passing in an integer vs Check if object by using instanceof - passing in an object vs Check if object by using instanceof - passing in a string vs Check if object by using instanceof - passing in a string object vs Check if object by using instanceof - passing in an integer vs Check if object by using typeof - passing in an object vs Check if object by using typeof - passing in a string vs Check if object by using typeof - passing in a string object vs Check if object by using typeof - passing in an integer

Created: one year ago by: Guest

Go to the latest result

Script Preparation code:

let objVal = {
  "a" : "a",
  "b" : "b"
};

let strObjVal = new String("hello");

let strVal = "hello";

let intVal = 23;

Tests:

Check if object by comparing value to an object instantiated from the value - passing in an object
let isObject = (objVal == Object(objVal) && !(objVal instanceof String));
Check if object by comparing value to an object instantiated from the value - passing in a string
let isObject = (strVal == Object(strVal) && !(strVal instanceof String));
Check if object by comparing value to an object instantiated from the value - passing in a string object
let isObject = (strObjVal == Object(strObjVal) && !(strObjVal instanceof String));
Check if object by comparing value to an object instantiated from the value - passing in an integer
let isObject = (intVal == Object(intVal) && !(intVal instanceof String));
Check if object by using instanceof - passing in an object
let isObject = (objVal instanceof Object && !(objVal instanceof String));
Check if object by using instanceof - passing in a string
let isObject = (strVal instanceof Object && !(strVal instanceof String));
Check if object by using instanceof - passing in a string object
let isObject = (strObjVal instanceof Object && !(strObjVal instanceof String));
Check if object by using instanceof - passing in an integer
let isObject = (intVal instanceof Object && !(intVal instanceof String));
Check if object by using typeof - passing in an object
let isObject = (typeof objVal != "object" && !(objVal instanceof String));
Check if object by using typeof - passing in a string
let isObject = (typeof strVal != "object" && !(strVal instanceof String));
Check if object by using typeof - passing in a string object
let isObject = (typeof strObjVal != "object" && !(strObjVal instanceof String));
Check if object by using typeof - passing in an integer
let isObject = (typeof intVal != "object" && !(intVal instanceof String));

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Check if object by comparing value to an object instantiated from the value - passing in an object
Check if object by comparing value to an object instantiated from the value - passing in a string
Check if object by comparing value to an object instantiated from the value - passing in a string object
Check if object by comparing value to an object instantiated from the value - passing in an integer
Check if object by using instanceof - passing in an object
Check if object by using instanceof - passing in a string
Check if object by using instanceof - passing in a string object
Check if object by using instanceof - passing in an integer
Check if object by using typeof - passing in an object
Check if object by using typeof - passing in a string
Check if object by using typeof - passing in a string object
Check if object by using typeof - passing in an integer

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/131.0.0.0 Safari/537.36

Browser/OS: Chrome 131 on Mac OS X 10.15.7

View result in a separate tab

Check if object by using typeof - passing in a string object

138.7M/s

Check if object by using instanceof - passing in an integer

135.2M/s

Check if object by using typeof - passing in an object

134.4M/s

Check if object by using typeof - passing in an integer

131.7M/s

Check if object by using instanceof - passing in a string

128.2M/s

Check if object by using typeof - passing in a string

119.4M/s

Check if object by using instanceof - passing in an object

111.3M/s

Check if object by using instanceof - passing in a string object

109.9M/s

Check if object by comparing value to an object instantiated from the value - passing in a string object

87.5M/s

Check if object by comparing value to an object instantiated from the value - passing in an object

85.1M/s

Check if object by comparing value to an object instantiated from the value - passing in an integer

32.4M/s

Check if object by comparing value to an object instantiated from the value - passing in a string

23.7M/s

View exact numbers

Test name	Executions per second
✓ Check if object by using typeof - passing in a string object	138,662,704 Ops/sec
Check if object by using instanceof - passing in an integer	135,158,704 Ops/sec
Check if object by using typeof - passing in an object	134,372,272 Ops/sec
Check if object by using typeof - passing in an integer	131,702,312 Ops/sec
Check if object by using instanceof - passing in a string	128,180,232 Ops/sec
Check if object by using typeof - passing in a string	119,427,768 Ops/sec
Check if object by using instanceof - passing in an object	111,343,112 Ops/sec
Check if object by using instanceof - passing in a string object	109,949,168 Ops/sec
Check if object by comparing value to an object instantiated from the value - passing in a string object	87,515,440 Ops/sec
Check if object by comparing value to an object instantiated from the value - passing in an object	85,065,192 Ops/sec
Check if object by comparing value to an object instantiated from the value - passing in an integer	32,428,818 Ops/sec
Check if object by comparing value to an object instantiated from the value - passing in a string	23,683,478 Ops/sec

Autogenerated LLM Summary (model gpt-4o-mini, generated one year ago):

LLMs can make mistakes. Check important info.

The benchmark focuses on three different methods to determine if a given variable is an object in JavaScript. The three approaches under testing are:

1. **Comparing Value to an Object Instantiated from That Value**: 
   - This method checks whether the variable is equal to an object created from the variable's value and also verifies that it is not an instance of `String`.
   - This approach is tested with various data types: objects, strings, string objects, and integers.
   - Pros: This method can provide a straightforward approach for checking if a variable is an object and concerns regarding certain JavaScript intricacies.
   - Cons: The equality check can lead to faulty results in some edge cases, particularly with primitive types, potentially introducing confusion regarding different value types.

2. **Using `instanceof`**:
   - This operator tests whether the variable is an instance of `Object` and confirms it is not an instance of `String`.
   - As with the first approach, it is tested against the same set of variable types.
   - Pros: `instanceof` is specifically designed for type-checking of instances and is generally more reliable for distinguishing objects versus non-objects.
   - Cons: It may fail with objects from different execution contexts (e.g., iframes) due to how JavaScript manages Object prototypes across contexts.

3. **Using `typeof`**:
   - The `typeof` operator is employed to determine if the type of the variable is not an "object" and also checks for `String` instances.
   - Again, tested across all variable types defined in the benchmark.
   - Pros: `typeof` can handle most primitive type checks easily and is quite fast.
   - Cons: The `typeof` operator has a couple of unexpected behaviors. For example, it returns "object" for arrays and `null`, leading to potential confusion when determining strict object types.

### Considerations
- Although these methods aim to ascertain the type of a variable, they can yield different results based on the variable type and the JavaScript environment.
- Edge cases need to be handled with care to avoid incorrect calls, particularly regarding primitive wrapper objects (such as `String`).

### Results Summary
The test results show varied performance in terms of executions per second for each of the methods. Using `typeof` generally appears to be the fastest in most cases, while using a comparison to object-instantiation tends to perform lower, especially for primitive data types.

### Alternatives
- **Object.prototype.toString.call(value)**: This method can be a more reliable way to accurately determine the type of an object, as it explicitly returns the internal class of the object (e.g., `[object Array]`, `[object Object]`, etc.).
- **Using utility libraries**: Libraries like Lodash or Underscore.js provide methods such as `_.isObject()` that encapsulate these checks robustly, ensuring consistent behavior across various data types and edge cases.

Overall, it’s important for developers to choose the method most appropriate for their specific context and to be aware of the nuances of type checking in JavaScript.