What are the differences between SVG and Canvas, and how to choose between them

SVG and Canvas are both technologies for drawing graphics on web pages, but they differ significantly in working principles, performance, and use cases:

1. Working Principles

• SVG: DOM-based vector graphics, each graphic element is an independent DOM node
• Canvas: Pixel-based bitmap, drawn via JavaScript on the canvas, ultimately generating a bitmap

2. Graphic Types

• SVG: Vector graphics, infinite scaling without quality loss
• Canvas: Bitmap, scaling causes quality loss

3. DOM Interaction

• SVG:

  • Each element can bind events (click, hover, etc.)
  • Can be styled via CSS
  • Supports standard DOM operations
  • Suitable for scenarios requiring interaction

• Canvas:

  • The entire canvas is one DOM element
  • Requires manual calculation of click positions and collision detection
  • Cannot directly style internal elements via CSS
  • Suitable for pure display scenarios

4. Performance Comparison

• SVG:

  • Good performance with few elements
  • Performance degrades with too many elements (thousands)
  • Suitable for icons, charts, simple animations

• Canvas:

  • Excellent performance with many elements
  • Stable performance when rendering large numbers of objects
  • Suitable for games, data visualization, complex animations

5. Accessibility

• SVG:

  • Supports screen readers
  • Can add title and desc elements
  • Search engines can index content
  • SEO friendly

• Canvas:

  • Poor accessibility
  • Requires additional ARIA support implementation
  • Search engines struggle to index content

6. File Size

• SVG:

  • Small file size for simple graphics
  • Large file size possible for complex graphics
  • Can be gzip compressed

• Canvas:

  • No file size involved (dynamically generated)
  • Exported image file size depends on resolution

7. Use Cases

SVG is suitable for:

• Icons and logos
• Simple to moderately complex charts
• Graphics requiring interaction
• Graphics requiring scaling
• Printing and high-quality output
• SEO-important content

Canvas is suitable for:

• Game development
• Big data visualization
• Complex animations
• Image processing
• Real-time rendering
• Performance-critical scenarios

8. Selection Recommendations

• Need interaction and accessibility: Choose SVG
• Need high-performance rendering of many objects: Choose Canvas
• Need vector scaling: Choose SVG
• Need pixel-level control: Choose Canvas
• Can combine both technologies to leverage their strengths