Javascript 如何从父组件调用子组件中的函数
单击Blog.js中呈现的按钮时,我想调用Blogpostreader.js中的函数showExtraBlogposts() 我尝试用onClick={blogpostreard.showExtraBlogposts()}调用它,它返回showExtraBlogposts()不是Blogpostreader的函数Javascript 如何从父组件调用子组件中的函数,javascript,reactjs,Javascript,Reactjs,单击Blog.js中呈现的按钮时,我想调用Blogpostreader.js中的函数showExtraBlogposts() 我尝试用onClick={blogpostreard.showExtraBlogposts()}调用它,它返回showExtraBlogposts()不是Blogpostreader的函数 import React from 'react'; import axios from 'axios'; import Blogpost from './Blogpost.js';
import React from 'react';
import axios from 'axios';
import Blogpost from './Blogpost.js';
class BlogpostReader extends React.Component {
constructor(props) {
super(props);
this.state = {
error: null,
isLoaded: false,
blogposts: [],
blogpostAmount: "",
counter: 1,
renderedBlogposts: []
};
}
componentDidMount() {
//API call
}
renderBlogpost(i) {
// Single blogpost rendered
}
showExtraBlogposts() {
for(this.state.counter; this.state.counter < (this.state.blogpostAmount + 2); this.state.counter++) {
this.state.renderedBlogposts.push(
<div key={this.state.blogposts[this.state.counter].id} className="col-12 col-sm-12 col-md-12 col-lg-6 col-xl-6 whole-blogpost">
{this.renderBlogpost(this.state.blogposts[this.state.counter])}
</div>)
}
this.forceUpdate();
}
render() {
this.state.blogpostAmount = this.state.blogposts.length;
for (this.state.counter; this.state.counter < this.state.blogpostAmount && this.state.counter < 5; this.state.counter++) {
this.state.renderedBlogposts.push(
<div key={this.state.blogposts[this.state.counter].id} className="col-12 col-sm-12 col-md-12 col-lg-6 col-xl-6 whole-blogpost">
{this.renderBlogpost(this.state.blogposts[this.state.counter])}
</div>)
}
return this.state.renderedBlogposts;
}
}
export default BlogpostReader;
从“React”导入React;
从“axios”导入axios;
从“./Blogpost.js”导入Blogpost;
类BlogpostReader扩展了React.Component{
建造师(道具){
超级(道具);
此.state={
错误:null,
isLoaded:false,
博客帖子:[],
blogpostAmount:“”,
柜台:1,,
renderedBlogposts:[]
};
}
componentDidMount(){
//API调用
}
renderBlogpost(一){
//单博客文章
}
showExtraBlogposts(){
for(this.state.counter;this.state.counter<(this.state.blogpostaunt+2);this.state.counter++){
this.state.renderedBlogposts.push(
{this.renderBlogpost(this.state.blogposts[this.state.counter])文件]
)
}
这个.forceUpdate();
}
render(){
this.state.blogpostmount=this.state.blogposts.length;
对于(this.state.counter;this.state.counter
我的博客组件如下所示:
import React from 'react';
import BlogpostReader from './BlogpostReader.js';
import BlogpostWriter from './BlogpostWriter.js';
class Blog extends React.Component {
render() {
return (
<div className="row">
<div className="col-12 col-sm-12 col-md-6 col-lg-6 col-xl-6">
<div className="wrap">
<BlogpostWriter className="blogpost-writer"/>
</div>
</div>
<div className="col-12 col-sm-12 col-md-6 col-lg-6 col-xl-6">
<div className="wrap">
<div className="row">
<BlogpostReader />
</div>
<div className="centered-button">
<button className="styled-button">Meer laden</button>
</div>
</div>
</div>
</div>
);
}
}
export default Blog;
从“React”导入React;
从“./BlogpostReader.js”导入BlogpostReader;
从“./BlogpostWriter.js”导入BlogpostWriter;
类Blog扩展了React.Component{
render(){
返回(
米尔·拉登
);
}
}
导出默认博客;
我如何解决这个问题
编辑
我修改了组件,以便BlogpostReader呈现按钮。我应该能够调用showExtraBlogposts()方法,但它总是给我一个错误,因为我的应用程序即使不单击按钮也会运行该方法。。。如何解决此问题?使用回调传递数据,在reactjs中不允许在父级中使用子函数
您不能真正从父组件调用子方法。执行此操作的“反应方式”是在父组件中,在状态中存储一个布尔值以跟踪它是否应该显示,然后通过子组件的道具将该布尔值传递给子组件。反应基于单向数据绑定的思想,这意味着父组件跟踪状态并通过道具传递状态和函数。这意味着父组件不能从子组件调用函数,为此,您需要使用其他库,如Redux