A quick recap

01 / 04

Firm ground before something new

From here on you will be learning a new tool: repetition.

Before that, though, let us bring back variables and branching from the last chapter. Everything you are about to learn is stacked on those two.

02 / 04

Variables and constants

Giving a value a name is a variable. const if you are not going to change it, let if you are.

And remember += and ++ for writing an update short.

const price = 320;let count = 0;count++;count++;console.log(`total ${price * count} yen`);

Result

total 640 yen

03 / 04

Branching

if is the machinery for "only run this when the condition holds". What to do when it does not goes in else, and another condition part way through goes in else if.

The conditions could be comparisons like > <= ===, or those combined with && and ||.

const temp = 26;if (temp >= 30) {  console.log("hot");} else if (temp >= 20) {  console.log("just right");} else {  console.log("cold");}

Result

just right

04 / 04

Putting the two together

Variables hold values; branching picks which way to go. With both of those you can write a program that behaves differently depending on the situation.

The repetition you learn from here always comes as a set with these two. Start by getting your hands moving on the recap questions.

const money = 500;const price = 380;if (money >= price) {  console.log(`change is ${money - price} yen`);} else {  console.log("not enough");}

Result

change is 120 yen