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JavaScript Web Components

JavaScript Web Components, Custom Elements, and Shadow DOM

Learn JavaScript Web Components with focused lessons on custom elements, Shadow DOM, templates, slots, component styling, event retargeting, and browser-native UI component architecture.

Web Components lessons

  1. Web Components overview

    Understand the browser standards behind native reusable components and how they fit with DOM APIs.

    Outcome: Decide when native Web Components are a good fit for reusable interface code.

    • JavaScript Web Components
    • web components tutorial
    • browser components
    Study From the orbital height

  2. Custom elements

    Define custom HTML elements, lifecycle callbacks, observed attributes, and customized built-ins.

    Outcome: Create reusable browser-native elements with predictable lifecycle behavior.

    • custom elements
    • JavaScript custom elements
    • HTMLElement
    Study Custom elements

  3. Shadow DOM

    Use Shadow DOM to encapsulate markup, behavior, and styles inside a component boundary.

    Outcome: Build components whose internals do not conflict with the surrounding page.

    • Shadow DOM
    • JavaScript shadow DOM
    • attachShadow
    Study Shadow DOM

  4. Templates

    Reuse inert HTML templates to stamp component DOM efficiently without parsing strings repeatedly.

    Outcome: Render component structure from a template element safely and consistently.

    • template element
    • HTML template
    • JavaScript templates
    Study Template element

  5. Slots and composition

    Compose light DOM and Shadow DOM with named slots, default slots, fallback content, and slot APIs.

    Outcome: Expose flexible extension points while keeping component internals isolated.

    • Shadow DOM slots
    • slot element
    • Web Components composition
    Study Shadow DOM slots, composition

  6. Shadow DOM styling

    Style hosts, slotted content, and component internals with :host, ::slotted, and CSS properties.

    Outcome: Design component styling hooks without leaking internal implementation details.

    • Shadow DOM styling
    • host selector
    • slotted CSS
    Study Shadow DOM styling

  7. Shadow DOM events

    Understand event retargeting, composed paths, and how custom events cross component boundaries.

    Outcome: Handle events from Web Components without breaking encapsulation.

    • Shadow DOM events
    • event retargeting
    • composedPath
    Study Shadow DOM and events