devlearn-javascript — reference

MDN quick links

<script src="app.js" defer></script>

Attribute	Effect
defer	Run after HTML parsed, order preserved
type="module"	ES modules, strict mode, defer implied

/** @type {{ id: string, text: string, done: boolean }[]} */
let todos = [];

const id = crypto.randomUUID?.() ?? String(Date.now());

Explain: stable id for delete/toggle.

function deleteTodo(id) {
  todos = todos.filter((t) => t.id !== id);
  render();
}

Teach filter as "keep todos whose id doesn't match."

async function loadTodos() {
  const response = await fetch('/api/todos');
  todos = await response.json();
  render();
}

Order: fetch returns Promise → await pauses function until data → json parses body.

Tool	Use
console.log	See values
breakpoint	Pause on line in Sources tab
Network tab	See fetch requests (apis skill)