所有的承诺都是平等的吗?

var someFunc = function() {
  return new Promise((resolve, reject) => {
      setTimeout(() => {
          resolve(37);
      }, 1000);
  });
};

var f1 = function() {
  return someFunc()
    .then(val => {
      return val + 1;
    });  
}

var f2 = function() {
  return new Promise(resolve => {
    someFunc()
    .then(val => {
      resolve(val + 1);
    });    
  });
}

var f3 = function() {
  someFunc().then(val => {
      return new Promise(resolve => {
          resolve(val + 1);
      });    
  });              
};

Angular 6 如果绑定变量的值在 then f1的。

这不起作用:(UI未更新)

public myClickHandler() {
   f1().then(val => this.uiBoundVar = val);
}

public myClickHandler() {
   f2().then(val => this.uiBoundVar = val);
   // This works too
   // f3().then(val => this.uiBoundVar = val);
}

From MDN Promise return value

悬而未决的承诺。然后异步调用处理程序函数(onFulfilled或onRejected)(只要堆栈为空)。调用处理程序函数后,如果处理程序函数:

返回一个值,则返回的promise将以返回值作为其值进行解析;