Grab Greco Interview Questions and Answers

You can pause a process in JavaScript using the setTimeout function.

• Use setTimeout function to delay the execution of a code block.

• Specify the time in milliseconds for the delay.

• Example: setTimeout(() => { console.log('Paused for 2 seconds'); }, 2000);

useMemo is used to memoize a value, while useCallback is used to memoize a function.

• useMemo is used to memoize a computed value and recompute only when its dependencies change.

• useCallback is used to memoize a callback function and re-create it only when its dependencies change.

• useMemo is useful for optimizing performance by avoiding unnecessary re-computations.

• useCallback is useful for optimizing performance by avoiding unnecessary re-creations of callback functions.

Null represents an intentional absence of any value, while undefined represents a variable that has been declared but not assigned a value.

• Null is explicitly assigned to a variable to indicate that it has no value.

• Undefined is the default value for variables that have been declared but not initialized.

• Null is a primitive value, while undefined is a type.

• Null is used to represent an empty value, while undefined is used to represent an uninitialized value.

• Example: let x = null;...read more

useEffect is a hook in React that allows for side effects in function components.

• useEffect is used to perform side effects in function components.

• It runs after every render by default.

• It can be used to fetch data, subscribe to events, or update the DOM.

• To mimic componentDidMount, pass an empty array as the second argument.

• To mimic componentDidUpdate, pass a variable or state that useEffect depends on.

Use the .replace() method in JavaScript to replace $ in jQuery

• Use the .replace() method in JavaScript to replace $ with another character or string

• Example: var str = 'jQuery is $ great'; str = str.replace('$', 'not'); // Output: 'jQuery is not great'

let is block scoped, var is function scoped, const is a constant variable.

• let is block scoped, meaning it is only accessible within the block it is declared in.

• var is function scoped, meaning it is accessible throughout the function it is declared in.

• const is a constant variable, its value cannot be reassigned once it is initialized.

Truthy values are values that evaluate to true in a boolean context, while falsy values are values that evaluate to false.

• Truthy values include non-empty strings, numbers other than 0, true boolean values, and objects.

• Falsy values include empty strings, the number 0, false boolean values, null, undefined, and NaN.

• Using double negation (!!value) is a common way to convert a value to its corresponding boolean representation.

React JS is a JavaScript library for building user interfaces.

• React JS is a declarative, efficient, and flexible JavaScript library for building user interfaces.

• It allows developers to create reusable UI components.

• React uses a virtual DOM to improve performance by updating only the necessary parts of the actual DOM.

• React follows a unidirectional data flow, making it easier to understand and debug.

• React can be used to build single-page applications, mobile apps, and even desk...read more