问题描述
我正在尝试使用 useContext
中的 preact
。看来我做错了什么,因为我的上下文给出了未定义的值。
这里是主文件:
const {render,h,createContext} = window.preact
import htm from 'https://unpkg.com/htm?module'
const html = htm.bind(h)
import SampleComp from './sample-comp.js'
export const ContextOne = createContext()
export const ContextTwo = createContext()
const RootComp = (props) => {
return html`
<ContextOne.Provider value=${'ContextOne'}>
<ContextTwo.Provider value=${'ContextTwo'}>
<${SampleComp}/>
</ContextTwo.Provider>
</ContextOne.Provider>
`
}
render(html`<${RootComp} />`,document.body);
这里是示例组件:
const {useContext} = window.preactHooks
const {h} = window.preact
import htm from 'https://unpkg.com/htm?module'
const html = htm.bind(h)
import {ContextOne,ContextTwo} from './index.js'
export default function SampleComp (props) {
const one = useContext(ContextOne)
const two = useContext(ContextTwo)
return html`<div>${one} - ${two}</div>`
}
我在这里做错了什么?我已经想了几个小时了,但不知道。
解决方法
我明白了。
在发布问题后,我意识到通过使用 htm 我需要将提供者包装在模板字符串中以成为一个变量。所以正确的是:
const RootComp = (props) => {
return html`
<${ContextOne.Provider} value=${'ContextOne'}>
<${ContextTwo.Provider} value=${'ContextTwo'}>
<${SampleComp}/>
</ContextTwo.Provider>
</ContextOne.Provider>
`
}