Function Drills
Switch between declarations, arrows, defaults, rest, and higher-order patterns until they feel automatic.
Step 1 of 6
Functions are the substrate
Closures, this, generics — every advanced topic in this module rests on confidence with the four function shapes:
- Declaration:
function add(a, b) { return a + b; } - Expression:
const add = function (a, b) { return a + b; }; - Arrow:
const add = (a, b) => a + b; - Method:
{ add(a, b) { return a + b; } }
Plus the parameter features: defaults, rest (...args), and destructuring. Let's drill them.