Loader
A loader (sometimes called a “loading spinner” or “busy indicator”) is a visual cue that communicates to users that a process or operation is actively in progress. Unlike a progress bar—which typically shows a measurable percentage—loaders often appear when the completion time is unknown or not easily quantifiable. They usually take the form of a rotating spinner, pulsating dot, or other simple animations, indicating that the system is working or fetching data.
Usage
Temporary Feedback: Whenever a task may take more than a moment, using a loader reassures users that the process hasn’t stalled.
Unknown Duration: Loaders often appear if the system can’t reliably provide a time estimate (e.g., variable network speed, unpredictable server response).
Inline vs. Full-Page:
Inline loaders appear within a component (e.g., a button or small area) if only a portion of the page is loading.
Full-page loaders may overlay or replace the entire view when the main content is not yet available.
Use cases
Displaying a spinning icon while fetching data from a server
Showing a rotating ring during a file upload when progress can’t be estimated accurately
Indicating that a page or module is loading dynamic content
Not to be confused with
Skeleton: A skeleton outlines the final layout with placeholder shapes, giving users a preview of where content will appear. A loader typically focuses on a single animated icon or area, indicating an ongoing operation without showing the eventual layout.
Progress Bar: Progress bars display a measurable percentage or fraction of a task’s completion. A loader shows indefinite activity, with no explicit progress measure.
Best practices
Minimal Distraction
Keep the loader simple (e.g., a small spinner or circle). Overly elaborate animations can be distracting or increase CPU usage.
Use calm, subtle motion—avoid flashing or rotating too quickly.
Appropriate Placement
If the entire page is waiting, consider a centered, full-page loader or overlay to block interaction.
For partial loads, place the loader inline near the relevant content (e.g., next to a button or inside a table row that’s fetching extra data).
Time-Outs & Fallbacks
If loading may fail or take too long, provide an error message or retry option rather than leaving the loader spinning indefinitely.
Monitor average load times and consider fallback behavior (like partial loading or default content) if the loader is displayed for too long.
Loading Text or Labels
If space allows, include a short message or label (e.g., “Loading…” or “Fetching data…”) to clarify the purpose.
This is particularly helpful for accessibility—screen readers can announce the text or
aria-labelassociated with the loader.
Keyboard & Screen Reader Accessibility
Indicate via ARIA attributes that content is “busy” or “loading” (e.g.,
aria-busy="true") so screen readers understand the state.If the loader appears in place of content, ensure focus management doesn’t trap keyboard users.
Consistent Style
Match the loader’s color palette, size, and shape to your brand or design system.
If multiple loaders are used across the app, keep their style consistent so users recognize them instantly.
Performance Sensitivity
For short operations (under a second), consider whether a loader is necessary—rapid flickering of a spinner can feel jarring.
A short delay (e.g., 300–500ms) before showing the loader can reduce flicker if tasks often complete quickly.
For longer tasks with an expected completion time, consider a progress bar instead, so users can track how far along the process is.
Summary
A loader provides a visual indication that a process is in progress when the completion time is indeterminate. By using a simple, non-intrusive animation, placing it near relevant content, and ensuring proper accessibility, loaders reassure users that the system is working. Pairing loaders with time-outs, fallback strategies, and cohesive styling in your design system ensures a smooth user experience, even during slow or unpredictable operations.
