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JLL Interview Questions and Answers
Q1. Program to find if substring is present in a given string without using predefined functions
Iterate through the given string to check if the substring is present.
Iterate through the given string and check if each character matches the first character of the substring.
If a match is found, check the subsequent characters to see if they form the substring.
Return true if the entire substring is found within the given string, otherwise return false.
Q2. Difference between traditional function and arrow function
Traditional functions are defined using the function keyword, while arrow functions are defined using a concise syntax with =>.
Traditional functions are hoisted, while arrow functions are not.
Arrow functions do not have their own 'this' keyword, they inherit it from the parent scope.
Arrow functions are more concise and easier to read compared to traditional functions.
Traditional functions are better for methods in objects, while arrow functions are better for callbacks or eve...read more
Q3. Program to find frequency of letters in a string
Program to find frequency of letters in a string
Create an object to store the frequency of each letter
Loop through the string and increment the count of each letter in the object
Convert the object into an array of strings with letter and frequency pairs
Q4. Difference between useState and useEffect
useState is used to manage state in functional components, while useEffect is used to perform side effects in functional components.
useState is used to declare state variables in functional components.
useEffect is used to perform side effects in functional components, such as data fetching, subscriptions, or manually changing the DOM.
useState does not trigger re-renders, while useEffect can be used to trigger re-renders based on dependencies.
useState can be used multiple time...read more
Q5. Usecase to create counter in react
Creating a counter in React to increment and decrement a value.
Create a state variable to store the count value
Use setState to update the count value
Render the count value in the component
Add buttons to increment and decrement the count value
Q6. What is Callback hell
Callback hell is a situation where multiple nested callbacks make the code difficult to read and maintain.
Occurs when multiple asynchronous operations are nested within each other
Leads to deeply nested code structure which is hard to understand
Can be avoided by using Promises, async/await, or modularizing code
Q7. Types of Promises
Promises in JavaScript are objects representing the eventual completion or failure of an asynchronous operation.
Promises can be in one of three states: pending, fulfilled, or rejected.
Promises can be chained using .then() to handle success and .catch() to handle errors.
Promises can be created using the Promise constructor or by using async/await syntax.
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