In Grade 1, you learned to update a variable using its own value, like score = score + 10. This is so common that JavaScript has shortcuts for it:
| Shortcut | Same as |
|---|---|
x += 5 | x = x + 5 |
x -= 5 | x = x - 5 |
x *= 5 | x = x * 5 |
x /= 5 | x = x / 5 |
x %= 5 | x = x % 5 |
x **= 2 | x = x ** 2 |
let coins = 100;
coins += 50;
console.log(coins);
coins -= 30;
console.log(coins);
coins *= 2;
console.log(coins);
coins /= 4;
console.log(coins);It prints
150 120 240 60
The += shortcut works on strings too, which is great for building up a message bit by bit:
let shoppingList = "Shopping list:";
shoppingList += " plantain,";
shoppingList += " eggs,";
shoppingList += " bread";
console.log(shoppingList);It prints
Shopping list: plantain, eggs, bread