Javascript 从JSON.file获取嵌套数据时出现问题
我有一个db.json文件,我只想在屏幕上显示年份。例如:1999年、2000年、2001年等 JSON文件:Javascript 从JSON.file获取嵌套数据时出现问题,javascript,json,reactjs,Javascript,Json,Reactjs,我有一个db.json文件,我只想在屏幕上显示年份。例如:1999年、2000年、2001年等 JSON文件: { "cronology": [ { "year": "1999", "description": "This is a description text" }, { "year": "2000",
{
"cronology":
[
{
"year": "1999",
"description": "This is a description text"
},
{
"year": "2000",
"description": "This is a description text"
},
{
"year": "2001",
"This is a description text"
},
{
"year": "2002",
"This is a description text"
}
]
}
import React, { Component } from 'react'
import { Scrollbars } from 'react-custom-scrollbars'
var data = require('./db.json');
class Cronology extends Component {
constructor(props) {
super(props)
this.state = {
cronology: [],
year: "",
description: ""
}
}
componentDidMount() {
this.setState({
cronology: data.cronology
})
}
render() {
return (
<ul>
{
Objct.keys(this.state.cronology).map(
(i) => {
return <li>i.year</li>
})
}
</ul>
}
}
export default Cronology;
我试过这样的方法,你可以看到下面这个反应组件,但它不适合我
React组件文件:
{
"cronology":
[
{
"year": "1999",
"description": "This is a description text"
},
{
"year": "2000",
"description": "This is a description text"
},
{
"year": "2001",
"This is a description text"
},
{
"year": "2002",
"This is a description text"
}
]
}
import React, { Component } from 'react'
import { Scrollbars } from 'react-custom-scrollbars'
var data = require('./db.json');
class Cronology extends Component {
constructor(props) {
super(props)
this.state = {
cronology: [],
year: "",
description: ""
}
}
componentDidMount() {
this.setState({
cronology: data.cronology
})
}
render() {
return (
<ul>
{
Objct.keys(this.state.cronology).map(
(i) => {
return <li>i.year</li>
})
}
</ul>
}
}
export default Cronology;
import React,{Component}来自“React”
从“react custom Scrollbars”导入{Scrollbars}
var data=require('./db.json');
类Cronology扩展组件{
建造师(道具){
超级(道具)
此.state={
权杖学:[],
年份:“,
说明:“”
}
}
componentDidMount(){
这是我的国家({
权变学:数据。权变学
})
}
render(){
返回(
{
key(this.state.cronology).map(
(i) =>{
返回- i.year
})
}
}
}
导出默认密码;
屏幕上没有显示任何渲染数据,也没有任何错误消息。如何解决此问题?仅使用地图
render() {
const cronology = this.state.cronology || []; // validate cronology
return (
<ul>
{
cronology.map(
(i) => {
return <li>i.year</li>
})
}
</ul>
}
render(){
const cronology=this.state.cronology | |[];//验证cronology
返回(
{
cronology.map(
(i) =>{
返回- i.year
})
}
}