Exercises: JavaScript Variable Scope

Standard Exercises

0. Create a function called countUp() that adds one to a global variable called ‘counter’. Check it with the following code.

var counter = 0;
countUp();
countUp();
console.log(counter);    // Should print 2

1. Figure out what value will be printed out by the console.log commands and then try it for yourself.

var name = "John";
function doSomething() { name = "Alex"; }

console.log(name);
doSomething();
console.log(name);

2. What is wrong with the following code (tip: Run it in the console to find out!)?

function doSomething() { name = "Alex"; }
console.log(name);

3. What is wrong with the following code (tip: Run it to see what value of ‘name’ is printed out!)?

var name = "John";

function updateGlobalName() { 
    var name = "Alex";
}

console.log(name);