prop.js - make DOM fast with a write-through cache

prop.js

// Set property of element.
// Uses a write-through cache to only set
// when value actually changes.
export const prop = (el, key, value) => {
  let cacheKey = Symbol.from(`prop.${key}`)
  if (el[cacheKey] != value) {
    el[cacheKey] = value
    el[key] = value
  }
}