Variables

1.What is the difference in var and let?

In JavaScript, var and let are used to declare variables but there is a difference in how they work.

The main difference is that var is function-scoped while let is block-scoped.

When you declare a variable with var, it is declared globally or locally to an entire function, regardless of block scope. This means that a variable declared with var within a block can still be accessed outside of that block.

On the other hand, when you declare a variable with let, it is only accessible within the block it was declared in. This means that a variable declared with let within a block cannot be accessed outside of that block.

Here is an example to illustrate the difference:

function example() {
  var x = 1;
  if (true) {
    var x = 2;
    console.log(x); // Output: 2
  }
  console.log(x); // Output: 2
}
 
function example2() {
  let x = 1;
  if (true) {
    let x = 2;
    console.log(x); // Output: 2
  }
  console.log(x); // Output: 1
}

In the example function, both var variables are accessible within the function, regardless of the block scope. In the example2 function, the let variable is only accessible within its block scope.