Handling Forms & User Input

What input analysis pattern does this demonstrate?

let lastValue = '';
input.addEventListener('input', e => {
  const newValue = e.target.value;
  const hasTyped = newValue.length > lastValue.length;
  const diff = hasTyped ? 
    newValue.slice(lastValue.length) : 
    lastValue.slice(newValue.length);
  lastValue = newValue;
  
  if (hasTyped) {
    handleNewCharacters(diff);
  } else {
    handleDeletion(diff);
  }
});

Input validation
Change tracking
Input diffing
This demonstrates input diffing, a pattern for analyzing precise input changes: 1) Tracks what characters were added or removed, 2) Distinguishes between typing and deletion, 3) Provides context about the specific changes made, 4) Useful for implementing advanced input features like auto-suggestions or syntax highlighting, 5) Can help with implementing undo/redo functionality, 6) Important for rich text editors or code editors.
Event delegation

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