As shown in the code, is the data generated after the foreach loop only the last one? My console.log(index); console can print out 0, 1, 2, 3, 4, but the pictures finally displayed on the page are all the pictures in case: 4.

 this.items.forEach((item:any) => {
                  // var index = this.items.indexOf(item);
                  // console.log(index);
                     // this.index.push(index);
                  switch (this.items.indexOf(item)){
                      case 0: this.imgSrc ='assets/liangshi.png';
                        break;
                      case 1: this.imgSrc ='assets/xiela.png';
                        break;
                      case 2: this.imgSrc ='assets/xuansuo.png';
                        break;
                      case 3: this.imgSrc ='assets/ganggou.png';
                        break;
                      case 4: this.imgSrc ='assets/gongqiao.png';
                        break;
                      default:
                        this.imgSrc = 'assets/ICON4TEST.png';
                  }
              });

This is the effect displayed on the page, all pictures are the last one