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Array isArray vs instanceof 2
(version: 0)
Comparing performance of:
Instanceof vs isArray
Created:
7 years ago
by:
Guest
Go to the latest result
Script Preparation code:
var test = [1,2,3,4]; var c;
Tests:
Instanceof
if ([1,2,3,4] instanceof Array) { c++; }
isArray
if (Array.isArray([1,2,3,4])) { c++; }
Rendered benchmark preparation results:
Suite status:
<idle, ready to run>
Run tests (2)
Previous results
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Test case name
Result
Instanceof
isArray
Fastest:
N/A
Slowest:
N/A
Latest run results:
Run details:
(Test run date:
one year ago
)
User agent:
Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/133.0.0.0 Safari/537.36
Browser/OS:
Chrome 133 on Linux
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Embed Benchmark Result
<iframe src="https://measurethat.net/Embed?id=588929" width="100%" height="500px"></iframe>
isArray
15.5M/s
Instanceof
15.1M/s
View exact numbers
Test name
Executions per second
✓
isArray
15,502,635 Ops/sec
Instanceof
15,063,881 Ops/sec
Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
Measuring JavaScript performance is crucial for creating efficient and scalable applications. Let's break down the provided benchmark definitions to understand what's being tested. **Benchmark Overview** The benchmark measures the performance difference between two approaches: 1. `instanceof` (using the `Array` constructor) 2. `Array.isArray()` (a modern method introduced in ECMAScript 2015) Both methods check if a given value is an array. The test aims to determine which approach is faster and more efficient. **Options Compared** The two options being compared are: 1. **Using `instanceof` with the `Array` constructor**: This method checks if the object passed in the parentheses has an instance of the `Array` class, which returns a boolean value indicating whether it's an array or not. 2. **Using `Array.isArray()`**: Introduced in ECMAScript 2015, this method provides a more concise and readable way to check if a given value is an array. **Pros and Cons** 1. **Using `instanceof` with the `Array` constructor**: * Pros: More explicit and clear, allowing developers to easily understand the intent behind the code. * Cons: May be slower due to the overhead of the `instanceof` operator and the need to check for a specific class. 2. **Using `Array.isArray()`**: * Pros: More concise, readable, and efficient, as it uses an optimized method specifically designed for array checks. * Cons: Requires ECMAScript 2015 support or later, making older browsers incompatible. **Other Considerations** When choosing between these two approaches: * **Code readability**: If code readability is more important than performance, `Array.isArray()` might be a better choice. * **Compatibility**: When targeting older browsers that don't support `Array.isArray()`, the `instanceof` method may be necessary. **Library and Special JS Features** There are no libraries used in this benchmark. However, note that ECMAScript 2015 is a standard language feature introduced by the European Computer Manufacturers Association (ECMA). **Special JS Feature** The test case uses a special JavaScript feature called "preamble code" (in this case, `var c;`) to define variables and control flow before running the actual benchmark. This approach allows for more flexibility in crafting custom benchmarks. Overall, this benchmark provides valuable insight into the performance differences between two commonly used methods for checking if a value is an array in JavaScript.
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