Q191. What is the difference between an attribute and a property?
Attributes are defined on the HTML markup whereas properties are defined on the DOM. For example, the below HTML element has 2 attributes: `type` and `value`, ```javascri...
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Q192. What is the purpose of ReactTestUtils package?
_ReactTestUtils_ are provided in the `with-addons` package and allow you to perform actions against a simulated DOM for the purpose of unit testing.
Q193. What is same-origin policy?
The same-origin policy is a policy that prevents JavaScript from making requests across domain boundaries. An origin is defined as a combination of URI scheme, hostname, ...
Q194. What is Jest?
_Jest_ is a JavaScript unit testing framework created by Facebook based on Jasmine and provides automated mock creation and a `jsdom` environment. It's often used for tes...
Q195. What is the purpose of void 0?
Void(0) is used to prevent the page from refreshing. This will be helpful to eliminate the unwanted side-effect, because it will return the undefined primitive value. It ...
Q196. What are the advantages of Jest over Jasmine?
There are couple of advantages compared to Jasmine: - Automatically finds tests to execute in your source code. - Automatically mocks dependencies when running your tests...
Q197. Is JavaScript a compiled or interpreted language?
JavaScript is an interpreted language, not a compiled language. An interpreter in the browser reads over the JavaScript code, interprets each line, and runs it. Nowadays ...
Q198. Give a simple example of Jest test case
Let's write a test for a function that adds two numbers in `sum.js` file: ```javascript const sum = (a, b) => a + b; export default sum; ``` Create a file named `sum.test...
Q199. Is JavaScript a case-sensitive language?
Yes, JavaScript is a case sensitive language. The language keywords, variables, function & object names, and any other identifiers must always be typed with a consistent ...
Q200. What is flux?
**Flux** is an **application architecture** (not a framework or library) designed by Facebook to manage **data flow** in React applications. It was created as an alternat...