How to use this book
Fifteen minutes, four times a day, for fifty days. Every chapter is sized to about fifteen minutes, including its exercises and quiz. Four chapters make a day. The 50-day plan shows where you are.
Start each day with your reviews. As you read, you’ll meet Quick recall boxes. Try to answer each one in your head before you reveal it, then say honestly whether you remembered. That one tap adds the card to your personal deck. The Review page then brings each card back just before you’d forget it: first after a few days, then weeks, then months. A few minutes a day is enough, and it is the difference between having read this book and knowing it.
Reading something again feels productive but fades fast. Pulling an answer out of your own memory is harder, and the effort is exactly what makes it stick. In a classic experiment, students who practised recalling a passage remembered more of it a week later than students who spent the same time rereading it.
Step through the diagrams. Diagrams marked Step through move only when you tap Next. Go at your own pace, and go back whenever something doesn’t click. The colours mean the same thing everywhere: if a field is orange in one picture, it is orange in all of them.
Type the code. Every Try it block is editable and runnable. On a phone, a row of symbol keys appears above the keyboard while you edit, and ⤢ opens the editor full screen. Your edits are saved in this browser.
Do the exercises before the solutions. Each exercise has tests, hints that reveal one at a time, and a worked solution that also shows the common wrong turns. Struggling for a few minutes first is not wasted time. That struggle is where the learning happens.
Your data stays with you. Your progress, review deck and code edits live only in this browser’s storage. The Review page can export a backup and import it on another device.