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Vue Progress Bar (0–100 with Threshold Colors)

By FrontendAtlas Team · Updated Jan 30, 2026

Build a Vue 3 progress bar for 0–100 with +10/−10 controls. Clamp values, display the percentage, and change the fill color by thresholds (red/orange/green) to communicate status clearly. Keep state in sync with UI at all times. Include accessibility notes (contrast, text labels), edge cases…

Render the progress bar UI as the main component.
Display the current progress percentage (e.g., "40%").

What you’ll build / What this tests

This premium vue coding focuses on Vue Progress Bar (0–100 with Threshold Colors). You’ll apply vue and reactivity thinking with easy level constraints. The prompt emphasizes Build a Vue 3 progress bar for 0–100 with +10/−10 controls. Clamp values, display the percentage,….

Learning goals

Translate the prompt into a clear vue API signature and return shape.
Apply vue, reactivity, composition-api techniques to implement vue progress bar (0–100 with threshold colors).
Handle easy edge cases without sacrificing readability.
Reason about time/space complexity and trade-offs in vue.

Key decisions to discuss

Define the exact input/output contract before coding.
Prioritize predictable edge-case handling over micro-optimizations.

Evaluation rubric

Correctness: covers required behaviors and edge cases.
Clarity: readable structure and predictable control flow.
Complexity: avoids unnecessary work for large inputs.
API discipline: no mutation of inputs; returns expected shape.
Testability: solution is easy to unit test.

Constraints / Requirements

Render the progress bar UI as the main component.
Display the current progress percentage (e.g., "40%").
Provide "+10%" and "−10%" buttons to increase/decrease progress by 10.
Clamp progress so it never goes below 0 or above 100.
Change the bar color based on thresholds (red/orange/green).
Initial progress starts at 0%.
Clicking "+10%" increases progress by 10 up to 100.
Clicking "−10%" decreases progress by 10 down to 0.
Progress never renders below 0% or above 100%.
Bar color changes by thresholds (example: 66 green).

Mini snippet (usage only)

// Example usage
const input = /* vue progress bar (0–100 with threshold colors) input */;
const result = solve(input);
console.log(result);

// Edge case check
const empty = input ?? null;
const fallback = solve(input);
console.log(fallback);

// Expected: describe output shape, not the implementation
// (no solution code in preview)

Common pitfalls

Mutating inputs instead of returning a new value.
Skipping edge cases like empty input, duplicates, or nulls.
Overlooking time complexity for large inputs.