Lecture 191:- Let in for loops

In ES6, the let keyword was introduced, which has block scope. This means that variables declared with let are only accessible within the block they are declared in. One of the main advantages of let over var is that it can be used in for loops to create block-scoped loop variables.

Consider the following example:

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for (let i = 0; i < 5; i++) {  console.log(i); } console.log(i); // throws an error because i is not defined

In this example, the let keyword is used to declare the loop variable i. Because let has block scope, i is only accessible within the for loop block. Therefore, the console.log(i) statement outside of the loop block will throw an error.

On the other hand, if var had been used instead of let, the loop variable i would have function scope, which means that it would be accessible outside of the for loop block:

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for (var i = 0; i < 5; i++) {  console.log(i); } console.log(i); // outputs 5

In this example, the loop variable i is declared using var, so it has function scope. Therefore, the console.log(i) statement outside of the loop block will output the value of i, which is 5.