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if(typeof <var> ===undefined) vs if(<var>)
(version: 0)
Comparing performance of:
no typeof vs typeof
Created:
4 years ago
by:
Guest
Jump to the latest result
Script Preparation code:
var a=undefined
Tests:
no typeof
var a=undefined if (a===undefined) true
typeof
var a=undefined if(typeof a===undefined) true
Rendered benchmark preparation results:
Suite status:
<idle, ready to run>
Run tests (2)
Previous results
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Test case name
Result
no typeof
typeof
Fastest:
N/A
Slowest:
N/A
Latest run results:
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Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
I'd be happy to explain the JavaScript benchmark being tested on MeasureThat.net. **Benchmark Definition** The benchmark definition consists of two JavaScript expressions that compare the behavior of `if(typeof <var> === undefined)` and `if(<var>)` when `<var>` is assigned a value of `undefined`. **Options Compared** There are two options compared: 1. **`typeof`**: This option checks if the variable `<var>` is of type `undefined`. 2. **No `typeof`**: In this case, it simply checks if `<var>` is equal to `undefined`, without using the `typeof` keyword. **Pros and Cons** Here's a brief analysis of each approach: * **`typeof`**: + Pros: More accurate when checking for `undefined` type, as `typeof undefined` returns `"undefined"`. + Cons: May be slower due to the extra operation required. * **No `typeof`**: Faster and more efficient, but may lead to incorrect results if `<var>` is not `undefined`. * Additional consideration: When `<var>` has a value other than `undefined`, `if(typeof <var> === undefined)` will evaluate to `false`, while `if(<var>)` will be `true`. This is because `typeof` returns the type of the variable as a string, whereas `<var>` is simply its value. **Library and Special JS Feature** There is no specific library being used in this benchmark. However, it's worth noting that MeasureThat.net uses a custom JavaScript engine to execute the benchmarks. **Test Cases** The test cases are designed to compare the behavior of these two expressions under different conditions. The first test case checks the expression without using `typeof`, while the second test case explicitly uses `typeof`. **Other Alternatives** If you're looking for alternative benchmarking tools, here are a few options: 1. **Benchmark.js**: A popular benchmarking library that supports various benchmarks, including JavaScript. 2. **jsperf**: An old-school JavaScript benchmarking tool that allows you to write and compare performance tests. 3. **Google's Benchmark**: A high-performance benchmarking framework that supports C++ and other languages. Keep in mind that MeasureThat.net is a specialized tool designed specifically for testing JavaScript benchmarks, so it may not be suitable for general-purpose benchmarking needs.
Related benchmarks:
typeof Undefined vs ===
Typeof x === 'undefined' vs x === undefined (test without syntax error)
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typeof number vs not typeof undefined vs undefined
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