blob: feb314ceb4f187860641392be0e198cf1940327b (
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import { magic } from '../magics'
magic('watch', (el, { evaluateLater, effect }) => (key, callback) => {
let evaluate = evaluateLater(key)
let firstTime = true
let oldValue
effect(() => evaluate(value => {
// JSON.stringify touches every single property at any level enabling deep watching
JSON.stringify(value)
if (! firstTime) {
// We have to queue this watcher as a microtask so that
// the watcher doesn't pick up its own dependencies.
queueMicrotask(() => {
callback(value, oldValue)
oldValue = value
})
} else {
oldValue = value
}
firstTime = false
}))
})
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