Course Review

Congratulations! You've finished the course and have mastered the beginning concepts. We've covered a lot of material, and now it's time for two final practice exercises where you will see how to use JavaScript to solve real-world problems. The first exercise reviews "assignment", "declaration", and "conditional statements" like if/else and switch, and "comparison" and "logical" operators using interactive examples.

Final Practice Exercise Review

comparison operators

 

A note on comparison operators

Comparison operators are used to test the conditions inside our conditional statements. We first looked at comparison operators back in our Basic math in JavaScript — numbers and operators article. Our choices are:

  • === and !== — test if one value is identical to, or not identical to, another.
  • < and > — test if one value is less than or greater than another.
  • <= and >= — test if one value is less than or equal to, or greater than or equal to, another.

We wanted to make a special mention of testing Boolean (true/false) values, and a common pattern you'll come across again and again. Any value that is not false, undefined, null, 0, NaN, or an empty string ('') actually returns true when tested as a conditional statement, therefore you can use a variable name on its own to test whether it is true, or even that it exists (that is, it is not undefined.) So for example:

let cheese = 'Cheddar';
 if (cheese) {
console.log('Yay! Cheese available for making cheese on toast.');
 } else {
console.log('No cheese on toast for you today.');
 }



And, returning to our previous example about the child doing a chore for their parent, you could write it like this:

let shoppingDone = false;
 let childsAllowance;

 if (shoppingDone) {
  childsAllowance = 10;
  } else {
  childsAllowance = 5;
}