在 ionic 中随机加载 Json 文件

Question

我有一个带有 *ngFor 的 div，它从 json 加载值。我需要从不同的 json 文件中随机加载值。 这里 div 从“mydata”获取值，下次我需要从另一个 json 获取值。我怎样才能做到这一点？ 我听说过 Math.floor((Math.random()。我该怎么做？或任何其他方法？

html file 
      <div class="row" *ngFor="let data of mydata">
       <div class="col">{{data.number}}</div>
       <div class="col">{{data.code}}</div>          
      </div>



ts file

import { Component } from '@angular/core';
import { NavController, NavParams } from 'ionic-angular';

@Component({
selector: 'page-showall',
templateUrl: 'showall.html'
})
export class ShowallPage {

 constructor(public navCtrl: NavController, public navParams: NavParams) {

 }

// i am providing data here instead of json for development.
  datas = [
{
  number: "1",
  code: "apple",

},
{
  number: "2",
  code: "orange",

},
{
  number: "3",
  code: "banana",

},{
  number: "50",
  code: "lemon",

}

  ];

  mydata = this.datas;

   // i am using this 'mydata' variable in *ngFor to get values

 }

Answer 1

在您创建的类中，您指定了从哪个 JSON 文件读取并将其分配给数据。

创建一个要读取的位置数组，并从构造函数中对其进行初始化。

public locations: Array<string>;

this.locations = ['firstLocation.json', 'secondLocation.json'];
let randomJsonFile = this.locations[Math.floor((Math.random() * this.locations.length) + 1)];

编辑：
（OP添加了一个更详细的问题）

  // Outside of the constructor (inside of the class)

  mydata: Array<Object>;
  datas0: Array<Object>;
  datas1: Array<Object>;
  datas2: Array<Object>;
  datasCollection: Array<Object>;

  // Inside of the constructor

      this.datas0 = [
        { number: "1", code: "apple0" },
        { number: "2", code: "orange0" },
        { number: "3", code: "banana0" },
        { number: "50", code: "lemon0" }
      ];

      this.datas1 = [
        { number: "1", code: "apple1" },
        { number: "2", code: "orange1" },
        { number: "3", code: "banana1" },
        { number: "50", code: "lemon1" }
      ];

      this.datas2 = [
        { number: "1", code: "apple2" },
        { number: "2", code: "orange2" },
        { number: "3", code: "banana2" },
        { number: "50", code: "lemon2" }
      ];

      this.datasCollection.push(this.datas0, this.datas1, this.datas2);

      this.mydata = this.datasCollection[Math.floor((Math.random() * this.datasCollection.length) + 1)];