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03. JavaScript Core

Use JavaScript to build real behavior in the browser.

  • Variables, conditionals, loops, functions.
  • Arrays and objects.
  • DOM selection and event handling.
  • Async basics: promises and fetch.
  • Error handling and debugging with DevTools.
  • Interactive todo app.
  • Weather app consuming a public API.
  • Small utility app with form validation.

You can fetch data from an API, update UI state, and debug common frontend issues.