JavaScript 'var' Keyword Interview Examples

Here are the top 5 examples of the var keyword in JavaScript that are helpful for interviews:

1. Declaring global variables:

The var keyword can be used to declare global variables, which are variables that are accessible from anywhere in the code. For example:

var name = "John Doe";

console.log(name); // Outputs "John Doe"

2. Declaring function-scoped variables:

The var keyword can also be used to declare function-scoped variables, which are variables that are only accessible within the function in which they are declared. For example:

function greet() {
  var greeting = "Hello, " + name + "!";

  console.log(greeting);
}

greet(); // Outputs "Hello, John Doe!"

 

3. Redeclaring variables:

The var keyword can be used to redeclare variables, which means that you can assign a new value to a variable that has already been declared. For example:

var name = "John Doe";

console.log(name); // Outputs "John Doe"

var name = "Jane Doe";

console.log(name); // Outputs "Jane Doe"

4. Function hoisting:

Function hoisting is a JavaScript feature that moves all function declarations to the top of the scope in which they are declared. This means that you can call a function before it is declared in the code. For example:

function greet() {
  console.log("Hello!");
}

greet(); // Outputs "Hello!"

5. Variable shadowing:

Variable shadowing is a JavaScript feature that allows you to declare a variable with the same name as a variable that is already declared in a higher scope. The variable in the lower scope will take precedence over the variable in the higher scope. For example:

var name = "John Doe";

function greet() {
  var name = "Jane Doe";

  console.log(name);
}

greet(); // Outputs "Jane Doe"

These are just a few examples of how to use the var keyword in JavaScript. The var keyword is a powerful tool, but it is important to use it carefully to avoid errors and unexpected behavior.

Here are some additional tips for using the var keyword in interviews:

• Avoid using the var keyword to declare global variables. Global variables can make your code difficult to maintain and debug.
• Prefer to use the let and const keywords to declare variables. let and const variables have block scope, which means that they are only accessible within the block in which they are declared. This can help to prevent variable shadowing and other errors.
• If you do need to use the var keyword, be sure to declare your variables at the top of the scope in which they are used. This can help to prevent function hoisting errors.