我無法從findIndex方法訪問我的類變量。 My whole class:    import { Component, Input, OnInit } from '@angular/core';import { History } from '../model/history';import { SharedService } from "../shared.service";@Component({  selector: 'app-details',  templateUrl: './details.component.html',  styleUrls: ['./details.component.scss']})export class DetailsComponent implements OnInit {  history: History[] = [    {      basic_text: { basic_text: 'text_1' },      summary: { summary: 'summary_1' },      tager: { tag_algorytm: true, tag_text: "tag_1" }    },    {      basic_text: { basic_text: 'text_2' },      summary: { summary: 'summary_2' },      tager: { tag_algorytm: false, tag_text: "tag_2" }    }  ];  basic_text: String = "Tekst podstawowy";  summary: String = "Streszczenie";  rating: String = "Ocenione zdania";  chosedText: string;  asd: string = 'asdad';  constructor(private sharedService: SharedService) { }  ngOnInit() {    this.sharedService.sharedMessage.subscribe(chosedText => this.chosedText = chosedText)  }  textFilter(h: History[]) {    let result: History[] = [];    var param = this.chosedText;    var foundIndex = h.findIndex(this.isEqualToSelectedText, param);    result.push(h[foundIndex])    return result;  }  // The function was moved out  private isEqualToSelectedText(element: History) {    return element.basic_text.basic_text === this.chosedText;  }}但如果我這樣做var x= h.findIndex(isEqualToSelectedText, 'text_1');一切正常。我嘗試從 isEqualToSelectedText 函數訪問我的類 varialb 。但我總是遇到這個錯誤。在findIndex運行期間，單詞“this”應等于“text_1”。你能幫助我嗎？