Introduction
Top 10:- Questions and Answers for improving and understanding JavaScript Programming Language. Learn and Understand JavaScript Programming like Pro.
1. Question: What is JavaScript?
Answer: JavaScript is a high-level, interpreted programming language primarily used for adding interactivity and dynamic behavior to web pages.
2. Question: How do you declare a variable in JavaScript?
Answer: You can declare a variable using the var, let, or const keyword, followed by the variable name, e.g., let myVar;.
3. Question: What is the difference between "null" and "undefined" in JavaScript?
Answer: "null" is an explicitly assigned value that represents the absence of any object value, while "undefined" indicates that a variable has been declared but has not been assigned a value.
4. Question: How do you add a comment in JavaScript?
Answer: In JavaScript, you can add a single-line comment using // or a multi-line comment using /* */.
5. Question: What is an array in JavaScript?
Answer: An array in JavaScript is a data structure that stores a collection of values, which can be of different data types, and can be accessed by their index.
6. Question: What is a function in JavaScript?
Answer: A function in JavaScript is a reusable block of code that performs a specific task. Functions can be called multiple times with different inputs.
7. Question: How do you write an "if" statement in JavaScript?
Answer: An "if" statement in JavaScript is written as follows:
javascriptif (condition) {
// Code to execute if the condition is true
}
8. Question: What is the purpose of the "addEventListener" method in JavaScript?
Answer: The addEventListener method is used to attach an event handler function to an HTML element, enabling it to respond to specific events (e.g., click, mouseover).
9. Question: How do you create an object in JavaScript?
Answer: You can create an object using object literal notation, like this:
javascriptconst myObject = { key1: 'value1', key2: 'value2' };
10. Question: What is a callback function in JavaScript?
vbnet**Answer:** A callback function in JavaScript is a function that is passed as an argument to another function and is executed after the completion of the parent function. It's commonly used for asynchronous operations.
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