Q321. What are the restrictions of web workers on DOM?
WebWorkers don't have access to below javascript objects since they are defined in an external files 1. Window object 2. Document object 3. Parent object
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Q322. What is a switching component?
A _switching component_ is a component that renders one of many components. We need to use object to map prop values to components. For example, a switching component to ...
Q323. What is the purpose of the "data-\*" attribute in HTML?
The data=\* attribute allows us to store additional information about an HTML element that is not otherwise displayed on the page, but may be useful to scripts that inter...
Q324. What are the Pointer Events supported in React?
_Pointer Events_ provide a unified way of handling all input events. In the old days we had a mouse and respective event listeners to handle them but nowadays we have man...
Q325. What is the purpose of <legend> tag?
The `` tag provides semantic caption or title for a `` element. It is optional but better for better to have for accessibility.
Q326. Why should component names start with capital letter?
If you are rendering your component using JSX, the name of that component has to begin with a capital letter otherwise React will throw an error as an unrecognized tag. T...
Q327. Which set operator for "searched but didn't buy"?
`MINUS` (Oracle) or `EXCEPT` (PostgreSQL/SQL Server): ```sql SELECT name FROM searchers WHERE product = 'X' EXCEPT SELECT name FROM buyers WHERE product = 'X'; ``` ---
Q328. Are custom DOM attributes supported in React v16?
**Note:** This question references React v16, which is outdated. The information below applies to React 16+, including current versions (React 18/19). Yes. Starting with ...
Q329. What is the purpose of the <picture> element in HTML5, and how is it used to optimize images?
The `` element in HTML5 is used to provide multiple versions of an image at different resolutions or sizes, and allows the browser to choose the best version to display b...
Q330. What is a callback function?
A callback function is a function passed into another function as an argument. This function is invoked inside the outer function to complete an action. Let's take a simp...