Javascript 如何分解包含函数的对象?
我有以下反应组件:Javascript 如何分解包含函数的对象?,javascript,reactjs,ecmascript-6,destructuring,Javascript,Reactjs,Ecmascript 6,Destructuring,我有以下反应组件: import { AppInterface } from 'pages/_app' export default class SiteNavBtn extends React.Component { static contextType = AppInterface render() { const { actions } = this.context const { toggleSiteNav } = actions
import { AppInterface } from 'pages/_app'
export default class SiteNavBtn extends React.Component {
static contextType = AppInterface
render() {
const { actions } = this.context
const { toggleSiteNav } = actions || {}
return(
<button className="site-nav-btn" onClick={ () => toggleSiteNav() }>
<i className="icon"><span>Open menu</span></i>
</button>
)
}
}
这是可行的,这意味着如果
This.context
未定义,当我现在单击按钮时,当然不会发生任何事情,但我没有得到错误,但是我相信我调用的是一个空函数。这是正确的还是有更好的方法来分解包含函数且可能未定义的对象 您可以将部分代码移动到单独的函数:
import { AppInterface } from 'pages/_app'
export default class SiteNavBtn extends React.Component {
static contextType = AppInterface
toggleSiteNav(){
const { actions } = this.context
const { toggleSiteNav } = actions || {};
if(typeof toggleSiteNav === 'function'){
toggleSiteNav ();
}
}
render() {
return(
<button className="site-nav-btn" onClick={ () => this.toggleSiteNav() }>
<i className="icon"><span>Open menu</span></i>
</button>
)
}
}
import{AppInterface}来自“pages/\u app”
导出默认类SiteNavBtn扩展React.Component{
静态contextType=AppInterface
toggleSiteNav(){
const{actions}=this.context
const{toggleSiteNav}=actions | |{};
if(toggleSiteNav的类型=='function'){
toggleSiteNav();
}
}
render(){
返回(
this.toggleSiteNav()}>
打开菜单
)
}
}
没错,但是您可以这样写:
const { actions: { toggleSiteNav = () => {} } = {} } = this.context;
...
<button onClick={toggleSiteNav} ...
const{actions:{toggleSiteNav=()=>{}}={}}=this.context;
...
如果回调不存在,我个人不会注册事件。否则,我会做一个通用的回调来处理点击请求,并处理如果所需的回调不存在该怎么办。在这种情况下,你可以把onClick={toggleSiteNav}
放进去。我觉得代码很好,正如前面提到的onClick={()=>toggleSiteNav()}
可以写成onClick={toggleSiteNav}
const { actions: { toggleSiteNav = () => {} } = {} } = this.context;
...
<button onClick={toggleSiteNav} ...
const { actions: { toggleSiteNav } = {} } = this.context;
...
<button onClick={toggleSiteNav ? toggleSiteNav : null} ...