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// getComponent is a function that returns a promise for a component | |
// It will not be called until the first mount | |
function asyncComponent(getComponent) { | |
return class AsyncComponent extends React.Component { | |
static Component = null; | |
state = { Component: AsyncComponent.Component }; | |
componentWillMount() { | |
if (!this.state.Component) { | |
getComponent().then(Component => { | |
AsyncComponent.Component = Component | |
this.setState({ Component }) | |
}) | |
} | |
} | |
render() { | |
const { Component } = this.state | |
if (Component) { | |
return <Component {...this.props} /> | |
} | |
return null | |
} | |
} | |
} | |
const Foo = asyncComponent(() => | |
System.import('./Foo').then(module => module.default) | |
) | |
const Bar = asyncComponent(() => | |
System.import('./Bar').then(module => module.default) | |
) | |
const App = () => | |
<BrowserRouter> | |
<Link to="/foo">Foo</Link> | |
<Link to="/bar">Bar</Link> | |
<Match pattern="/foo" component={Foo} /> | |
<Match pattern="/bar" component={Bar} /> | |
</BrowserRouter> | |
export default App |
I have the same question as @budarin.
How we can add progress until component not import.
I want to use this type of progress.
@nateq314 This should only be necessary if you're using something other than webpack. Using webpack the module only gets fetched one time, even if you're not caching the component in the static field.
How do I pass props to the lazy loaded component? I see that {...this.props}
has been used, but you can't pass properties to the AsyncComponent. Am I missing something?
I'm currently using something like this:
export default function asyncComponent(getComponent, props = {}) {
return class AsyncComponent extends Component {
state = {};
componentWillMount() {
getComponent().then(({ default: component }) => {
this.setState({ Component: component });
});
}
render() {
const { Component } = this.state
return Component ? <Component {...props} /> : null;
}
};
}
The route entry looks like this:
<Route path="/about" component={asyncRoute(() => import('./About'), { title: "About" })} />
Nice!!!
I would use FetchedComponent
or something internally instead of Component
(since you're probably already importing that symbol (Component
)).
Other than that awesome!
Hello everyone!
I'm using this code:
import React from "react"; import { BrowserRouter as Router, Route, Link, Switch, Redirect, Match } from "react-router-dom"; // import Bundle from "Bundle/Bundle"; // import PedidoApp from "bundle-loader?lazy!./PedidoApp"; // import PedidoForm from "bundle-loader?lazy!./pedidoform"; // getComponent is a function that returns a promise for a component // It will not be called until the first mount const asyncComponent = getComponent => { return class AsyncComponent extends React.Component { static Component = null; state = { Component: AsyncComponent.Component }; componentWillMount() { if (!this.state.Component) { getComponent().then(({ default: Component }) => { AsyncComponent.Component = Component; this.setState({ Component }); }); } } render() { const { Component } = this.state; if (Component) { return <Component {...this.props} />; } return null; } }; }; const PedidoApp = asyncComponent(() => import("./PedidoApp")); const PedidoForm = asyncComponent(() => import("./pedidoform")); class Root extends React.Component { render() { return ( <Router> <div> <Link to="/pedido-1">Pedido</Link> <Link to="/pedido-1/add">Agregar</Link> <Route pattern="/pedido-1" component={PedidoApp} /> <Route pattern="/pedido-1/add" component={PedidoForm} /> <Redirect path="*" to="/pedido-1" /> </div> </Router> ); } } export default Root;But it shows both components at the same time. How do I do in order to show
<PedidoApp/>
by default (Home) and when I click the Add button (or edit) show<PedidoForm/>
???Thank you
You have to use Either <switch>
component to wrap routes (or) Exact
Attribute on <Route>
Hello!
Writing an async component like this in TypeScript:
export function routeAsyncComponent(getComponent: () => Promise<React.Component>) {
interface IRouteAsyncComponentState {
Component: React.Component;
}
return class RouteAsyncComponent extends React.Component<any, IRouteAsyncComponentState> {
static Component: React.Component = null;
state = { Component: RouteAsyncComponent.Component };
componentWillMount() {
if (!this.state.Component) {
getComponent().then(Component => {
RouteAsyncComponent.Component = Component;
this.setState({ Component });
});
}
}
render() {
const { Component } = this.state;
if (Component) {
return <Component {...this.props} />;
}
return null;
}
}
}
TypeScript complains on return <Component {...this.props} />;
:
Type assertion using the '<>' syntax is forbidden. Use the 'as' syntax instead. (no-angle-bracket-type-assertion)tslint(1)
Type assertion on object literals is forbidden, use a type annotation instead. (no-object-literal-type-assertion)tslint(1)
Cannot find name 'Component'.ts(2304)
so dirty and so good, bro
Thank you for this brilliant code. I've been using this code very usefully.
Since
System.import
is deprecated, you have to useimport
.Additionally, rather than doing
module => module.default
for every routes, you can remove some unnecessary codes by doing({default: Component}) => ...
in componentWillMountFull Code:
function asyncComponent(getComponent) { return class AsyncComponent extends React.Component { static Component = null; state = { Component: AsyncComponent.Component }; componentWillMount() { if (!this.state.Component) { getComponent().then(({default: Component}) => { AsyncComponent.Component = Component this.setState({ Component }) }) } } render() { const { Component } = this.state if (Component) { return <Component {...this.props} /> } return null } } } const Foo = asyncComponent(() => import('./Foo')) const Bar = asyncComponent(() => import('./Bar'))
Can't figure out why .default
is needed
@budarin @AndreGajdos It's memoization. It's caching it for the next time the component is used. First time it will do the fetch. Every time thereafter it will already be there in the static Component field.