Javascript Class 内的承诺

Question

Fun with promises today ...我想弄清楚为什么我不能参考this.promise用另一种方法解决它，它总是空。

感谢任何启发:)

export default class Example {
  constructor() {
    this.promise = null
  }

  test() {
    this.promise = new Promise((resolve, reject) => {
      this.something()
    }).then(resolve => {
      // resolved, do something else
    }).catch(reject => {
      console.log('reject', reject)
    })
  }

  something() {
    this.promise.resolve()
  }
}

Answer 1

您正在尝试在 something 中使用 this.promise，然后它的值从 null 更改。另一种方法是将 resolve 作为参数传递：

class Example {
  constructor() {
    this.promise = null;
  }
  test() {
    this.promise = new Promise((resolve, reject) => {
      this.something(resolve);
    }).then(result => {
      console.log('resolve', result);
    }).catch(error => {
      console.log('reject', error);
    });
  }
  something(resolve) {
    resolve(1);
  }
}
const example = new Example();
example.test();