Detecting an undefined object property (49 answers) How to check a not-defined variable in JavaScript (15 answers) How to handle 'undefined' in JavaScript [duplicate] (3 answers) How can I check if a variable exist in JavaScript? (8 answers)
As many know, (0 == "") is true in JavaScript, but since 0 is a value and not empty or null, you may want to test for it. The following two functions return true only for undefined, null, empty/whitespace values and false for everything else, such as numbers, Boolean, objects, expressions, etc.
I usually just test javascript performance, how long script runs. jQuery Lover gave a good article link for testing javascript code performance, but the article only shows how to test how long your javascript code runs.
npm test -- bar.spec.js In 2015: In order to run a specific test, you'll need to use the jest command. npm test will not work. To access jest directly on the command line, install it via npm i -g jest-cli or yarn global add jest-cli. Then simply run your specific test with jest bar.spec.js. Note: You don't have to enter the full path to your ...
In JavaScript, it's not always as straightforward as it should be to reliably check if a value is a number. It's common for devs to use +, -, or Number () to cast a string value to a number (for example, when values are returned from user input, regex matches, parsers, etc).
In javascript, when using an if statement with multiple conditions to test for, does javascript test them all regardless, or will it bail before testing them all if it's already false? For exampl...
I have a test 'works with nested children' within the file fix-order-test.js. Running the below runs all the tests in the file. jest fix-order-test How do I run only a single test? The below does...
Is there a way to execute JavaScript and display the results using Visual Studio Code? For example, a script file containing: console.log('hello world'); I assume that Node.js would be needed but...
I use Mocha to test my JavaScript stuff. My test file contains 5 tests. Is that possible to run a specific test (or set of tests) rather than all the tests in the file?
