Modern JavaScript in the Browser
Learn to use JavaScript in the browser to build and ship a real, data-driven app.
About the Course
You know the JavaScript language — values, functions, arrays, objects. Now comes the part that makes it feel worth it: making a page actually do something. React to a click, fetch data from an API, render it to the screen, and keep it all in sync as the user moves around. This is where most people's mental model breaks, because the browser adds a runtime, events, and asynchronous code all at once.
This course works through that, one piece at a time. Across thirteen sections you'll cover how JavaScript actually runs (the event loop), the browser environment, the DOM, events, forms, asynchronous code, and fetching data with fetch and async/await — each in real depth, not a quick tour. Then you'll build a movie discovery app: search a real API as you type, render results, view details, save films to a watchlist that survives a reload, and deploy the whole thing to a live URL. Every concept lands inside that build.
The whole course is text, and that's deliberate. You can copy code without scrubbing through a video, search a lesson for the bit you half-remember, and come back to the section on the event loop six months from now when you actually need it. It's the format you already reach for when you're stuck, turned into a course.
This is Part 2 of two. Part 1, Modern JavaScript: The Fundamentals, teaches the language this course assumes. By the end of this part, you'll build data-driven browser apps on your own — and you'll have the mental model you need before picking up React, Vue, or any framework.
What You'll Build
You'll build a movie discovery app with vanilla JavaScript. It searches a public movie API as you type, renders results to the page, shows details for any film, and lets you save films to a watchlist that persists across reloads with localStorage. The code is split into ES modules, handles loading and error states like a real app, and ends deployed to a live URL.
What You'll Learn
- Explain how the event loop, task queue, and microtask queue run your code
- Work with the browser environment — window, location, and the History API
- Select, create, and update DOM elements, and render data to the page without XSS holes
- Handle events with delegation, bubbling, custom events, debouncing, and throttling
- Read, validate, and collect form input, and give users clear feedback
- Write asynchronous code with promises, async/await, and Promise.all
- Fetch from a real API — building query strings and cancelling stale requests
- Split a project into ES modules and persist state with localStorage
- Debug, handle failures, and ship an accessible app to a live URL
Prerequisites
- Comfortable writing JavaScript — arrays, objects, functions, closures, and destructuring. Part 1, Modern JavaScript: The Fundamentals, gets you exactly here.
- Comfortable with HTML and CSS
- A code editor and a modern browser
Who This Course Is For
- Developers who know the JavaScript language and want to build real things in the browser
- Graduates of Part 1 ready to take the language to the DOM and real APIs
- Front-end learners who want vanilla JavaScript solid before picking up React or Vue
