Every Salesforce developer working with Lightning Web Components (LWC) eventually runs into the same truth: everything comes back to JavaScript.
LWC isn’t its own language. It’s a framework built entirely on modern JavaScript. Your templates, events, rendering logic, and even the reactivity model all depend on it.
For a deeper look at the framework itself, see the official Salesforce LWC documentation.
That’s why this series starts with JavaScript. If you master JS, you’ll master LWC. If you only skim the surface, you’ll keep hitting confusing bugs, rendering issues, and missed opportunities.
This first post shows why JavaScript is the foundation of LWC and sets up the roadmap for everything coming next — variables, functions, events, async patterns, and ES6+ features.
Why This Matters
Every Lightning Web Component you build is powered by JavaScript. LWC isn’t a new language. Instead, it’s a framework that wraps modern JavaScript and enforces Salesforce’s rules (security, reactive rendering, modularity).
If you don’t know JavaScript deeply, you’ll keep hitting walls. However, if you do, you’ll fly.
This series strips LWC down to its core: JavaScript. Over the next 14 posts we’ll cover variables, functions, arrays, events, async calls, ES6+ features, and everything in between. Each piece is practical, tied to LWC, and ready to use.
JavaScript Lightning Web Components at the Core
Think of LWC as a thin layer on top of JavaScript:
- Template (.html) — Declarative markup.
- Component (.js) — Your JavaScript class drives state, data, and events.
- Metadata (.xml) — Tells Salesforce where your component can live.
The only logic engine here is JavaScript. No Apex, no hidden framework magic. Just JS.
When you extend LightningElement, you’re extending a JS class. When you handle events, you’re using JS event propagation. Even your template re-renders only because the JS engine tells it to.
Example: Small but Powerful
Here’s the simplest example. Nothing Salesforce-specific, just JavaScript driving output.
import { LightningElement } from 'lwc';
export default class HelloWorld extends LightningElement {
message = 'Hello, JavaScript!';
changeMessage() {
this.message = 'Updated at ' + new Date().toLocaleTimeString();
}
}Template:
<template>
<lightning-card title="Demo">
<p>{message}</p>
<lightning-button
label="Click Me"
onclick={changeMessage}>
</lightning-button>
</lightning-card>
</template>
Nothing here works without JavaScript. The variable, the method, the event are all JS.
Flow of Execution
Here’s how the engine runs under the hood:
- Browser executes JavaScript.
- JavaScript powers the LWC runtime.
- Runtime updates the Shadow DOM.
- UI reflects the state.
That’s why every post in this series is focused on JavaScript first, Salesforce second.
Roadmap: What’s Coming Next
We’ll cover, one by one:
- Variables and Scope in LWC Context
- Functions and Arrow Functions
- Objects and Arrays
- Template Rendering with Loops and Conditionals
- Events and Callbacks
- Destructuring and Spread Operators
- Classes in JavaScript (and Why LWC Uses Them)
- Modules and Imports/Exports
- Promises and Async/Await
- Error Handling
- JSON and Data Structures
- DOM Basics You Still Need
- JS Events vs. LWC Events
- ES6+ Features Every LWC Dev Should Use
Each one will be self-contained. Each one will have code, flow, and a takeaway you can apply immediately.
Takeaway
JavaScript isn’t optional in LWC. It is the foundation of everything you build.
- Templates only update because JavaScript drives reactivity.
- Events only propagate because JavaScript powers the engine.
- Your component logic is nothing more than a JavaScript class.
If you treat JavaScript as a side skill, you’ll always struggle with LWC. But if you embrace it as the engine, your components become simpler, faster, and easier to reason about.
This series is about giving you that foundation. Next up: Variables and Scope in LWC — the details that trip up even seasoned developers.
