| Objects, Functions, and Classes | 25% | Object creation and property access, functions and closures, the this keyword and binding, ES6 classes, and prototypal inheritance. The single largest domain, and the one where scope and closures trip people up. |
| Variables, Types, and Collections | 23% | Primitive versus reference types, coercion and equality, hoisting, let and const versus var, and collections including arrays, Map, and Set. Expect questions on what a snippet actually evaluates to. |
| Browser and Events | 17% | DOM traversal and manipulation, event handling, bubbling and capturing, and the browser runtime. This is the front-end half of the exam and where Lightning Web Component work maps most directly. |
| Asynchronous Programming | 13% | Callbacks, promises, async and await, and the event loop. Questions often ask about execution order or how promise chains resolve, so understanding the microtask queue helps. |
| Server Side JavaScript | 8% | Node.js fundamentals: modules and npm, the module system, streams, and the server-side event loop. A smaller domain, but you cannot skip Node entirely. |
| Debugging and Error Handling | 7% | try and catch, throwing and handling errors, error objects, and using the console and developer tools to trace problems. |
| Testing | 7% | Unit testing concepts, assertions, and how to structure tests. You do not need one specific framework memorized, but you should know the ideas. |