无法读取未定义的属性“推送”？ [复制]

Question

我有以下简单的代码：

  export class Years {

      private years: number[];
      private currentYear: number;

      constructor() {
        this.currentYear = new Date().getFullYear();
        this.years.push(this.currentYear + 1);
        for (let i = this.currentYear; i < this.currentYear - 5; i--) {
          this.years.push(i);
        }
      }
}

它给了我一个错误：Cannot read property 'push' of undefined??为什么如果我有正确的数据类型作为数组？

Answer 1

你必须初始化年​​为空数组，否则为空

 private years: number[] = [];