Variables which are declared within a function, as well as the function parameters have local scope. That means, they are only visible within that function.

Here is a function myLocalScope with a local variable called loc.

function myLocalScope() {
  var loc = "foo";
  console.log(loc);
}
myLocalScope(); // "foo"
console.log(loc); // "undefined"

loc is not defined outside of the function.