Nested loops and scope in JavaScript

If we have a loop within a loop, then the variables declared in the outer loop will be available in the inner one. In the following example, the variable num is available in the inner loop:

for (let i = 0; i <= 9; i++) { let num = 3; for (let j = 0; j <= 9; j++) { console.log(num); // shows 3 } }

But outside the outer loop, the variable num is not available:

for (let i = 0; i <= 9; i++) { let num = 3; for (let j = 0; j <= 9; j++) { } } console.log(num); // throws an error

Variables declared in the inner loop are not accessible from the outside:

for (let i = 0; i <= 9; i++) { for (let j = 0; j <= 9; j++) { let num = 3; } console.log(num); // throws an error } console.log(num); // throws an error
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