So with Proxy + Reflect together, we could easily make a JavaScript object observable, and then, reactive. What we need to do is just encapsulate them into a new pattern or more friendly APIs. Component Registration Non-Prop Attributes As you can see, compared to Vue 2 in which to create a new Vue component it was necessary to create a Typescript class and extend Vue using class MyClass extends Vue {}, now Vue 3 offers a defineComponent() function. // Will print the counter every time it's mutated. You should write Vue.$set(this.list, index, newItem) instead. So far, Vue didn't change the reactivity mechanism. And there is no way to worry about whether or not I write a React hook outside a React component or inside a conditional block. With ES2015+, the new Reactivity APIs and its independent package, Composition APIs, Vue 3.0, and more amazing stuff in the ecosystem and community. From now on, you could think about it: with reactivity APIs, what else amazing stuff could you make? If you would like to see all the live version of the code sample about explaining main mechanism of reactivity system in Vue from 0.x to 3.0. Access data/functions outside the component instance, mostly it happens when we set a template ref on a sub Vue component. This is equivalent to 2.x's Vue.observable() and was renamed to avoid confusion with RxJS observables. // Do the similar thing with more options, // could use a,b,c,d,e,f in template and `this`, // and rename it before you pass it into the template, https://codesandbox.io/s/vue-reactivity-tests-1-jm3d4, https://codesandbox.io/s/vue-reactivity-tests-2-vyykh, https://gist.github.com/Jinjiang/f9b6f968af980cfd21cfc713e59db91b, Every time we set a value into a property, it will call the setter, which will re-evaluate those related calculations inside the, So next time when some data changes, it will find out all related calculations inside the corresponding. Prerequisites for using props in Vue. A property: Hello Vue! Vue 2 offered the Provide/Inject API and now it's been enhanced and improved in Vue 3. You may be familiar with it, maybe not. This is an example of passing data through all the components. So the code is almost the same to above: The only difference is there is no watch and watchEffect. ref can directly be assigned to a single variable or constants, while reactive can be used as the usual data function we use often in Vue 2.0, it will make the whole Object it covers to be reactive. It seems nothing different to the former version so far. reactive() takes an object and returns a reactive proxy of the original. You'll learn much more about type checks and other prop validations further down this page. But this time, in Vue 3.0, it provides more util APIs, like markRaw we mentioned before. In addition, Vite is highly extensible via its Plugin API and JavaScript API with full typing support. Ref is used to declare reactive variables from primitive types such as: String; Number; BigInt; Boolean; Symbol; Null; Undefined; For example: They are born to reactivity systems! props: { songID: String }, setup (props) { watchEffect(() => console.log(props.songID)) } 2. The reactive system was rewritten to utilize JavaScript’s proxies. A ref could help you to hold a reference for a reactive value. You don't need Vue.$set anymore. This post is suited for developers of all stages including beginners. Understanding Vue 3 Ref for Reactive Variables. -->, , // all behaviors of a proxy by operation types, // will call `track()` & `trigger()` when get/set by index, // will call `trigger()` when set `length`, // set an invisible skip flag to raw data, // create a proxy only when there is no skip flag on the data, // output: x = 1, y = 2, x + y = 3, sum = 6. -->, , , , , ,