[英]TypeError: undefined is not an object (TS)
我试图将响应数组设置为我创建的接口(ApiPosts []),并且在尝试将帖子var更新到响应数组时遇到了这个奇怪的错误。 TypeError: undefined is not an object (evaluating 'this.posts = resText')
现在,响应是一个JSON对象数组。 当我console.log(res)
我得到一个预期的对象数组的代码如下:
import { Component, OnInit } from '@angular/core';
import { HttpClient } from '@angular/common/http';
import { post } from 'selenium-webdriver/http';
import { Injectable } from '@angular/core';
import { map, filter, catchError, mergeMap } from 'rxjs/operators';
@Component({
selector: 'app-my-likes',
templateUrl: './my-likes.component.html',
styleUrls: ['./my-likes.component.css']
})
export class MyLikesComponent implements OnInit {
posts:ApiPosts[];
constructor(private http:HttpClient) { }
ngOnInit() {
var data = null;
var xhr = new XMLHttpRequest();
xhr.withCredentials = false;
xhr.addEventListener("readystatechange", function () {
if (this.readyState === 4) {
var res = JSON.parse(this.responseText);
console.log(res);
setRes(res);
}
});
xhr.open("GET", my url);
xhr.setRequestHeader("content-type", "application/json");
xhr.setRequestHeader("x-apikey", my key);
xhr.setRequestHeader("cache-control", "no-cache");
xhr.send(data);
function setRes(resText) {
this.posts = resText;
console.log(resText);
}
}
}
interface ApiPosts {
_id: string,
address: string,
price: number,
rooms: number,
sqmt: number,
_mock: boolean
}
这是responseText即时获取的示例:
[{
"_id": "5bc98372f27689550002c99d",
"address": "979 Parisian Divide Suite 335\nTonistad, TX 33097",
"price": 1472,
"rooms": 6,
"sqmt": 984,
"_mock": true
}, {
"_id": "5bc98372f27689550002c9a9",
"address": "416 Barbara Dale\nLake Velva, GA 83588",
"price": 2028,
"rooms": 8,
"sqmt": 1518,
"_mock": true
}, {
"_id": "5bc98372f27689550002c9a3",
"address": "3109 Amely Stream\nJohnsonmouth, UT 83874",
"price": 3435,
"rooms": 11,
"sqmt": 1891,
"_mock": true
}]
我在角度6上做它是否有任何区别
在方法中使用function
, this
引用的不是当前类,而是参见here 。
window
global
undefined
的:
window.xxx()
参见此代码段,例如,一个输出undefined
,另一个输出window
:
'use strict' function abc() { console.log(this) } abc() // outputs undefined window.abc() // outputs the window object
现在,如果我们删除strict,则它们都将输出窗口:
function abc() { console.log(this) } abc() // outputs the window object window.abc() // outputs the window object
您需要做的是在方法本身内创建一个引用,然后在函数中使用该引用,如下所示:
ngOnInit() {
// Your other stuff here...
let $this = this;
function setRes(resText) {
$this.posts = resText;
}
}
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.