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Aug 25th, 2019
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  1. export function updateDomProperties(dom, prevProps, nextProps) {
  2. const isEvent = name => name.startsWith("on");
  3. const isAttribute = name => !isEvent(name) && name != "children";
  4.  
  5. // Remove event listeners
  6. Object.keys(prevProps)
  7. .filter(isEvent)
  8. .forEach(name => {
  9. const eventType = name.toLowerCase().substring(2);
  10. dom.removeEventListener(eventType, prevProps[name]);
  11. });
  12.  
  13. // Remove attributes
  14. Object.keys(prevProps)
  15. .filter(isAttribute)
  16. .forEach(name => {
  17. dom[name] = null;
  18. });
  19.  
  20. // Set new attributes
  21. Object.keys(nextProps)
  22. .filter(isAttribute)
  23. .forEach(name => {
  24. dom[name] = nextProps[name];
  25. });
  26.  
  27. // Set new eventListeners
  28. Object.keys(nextProps)
  29. .filter(isEvent)
  30. .forEach(name => {
  31. const eventType = name.toLowerCase().substring(2);
  32. dom.addEventListener(eventType, nextProps[name]);
  33. });
  34. }
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