The source for this interactive demo is stored in a GitHub repository. If you'd like to contribute to the interactive demo project, please clone https://github.com/mdn/interactive-examples and send us a pull request.

语法

Promise.resolve(value);
Promise.resolve(promise);
Promise.resolve(thenable);

参数

value

将被Promise对象解析的参数。也可以是一个Promise对象，或者是一个thenable。

返回值

返回一个解析过带着给定值的Promise对象，如果返回值是一个promise对象，则直接返回这个Promise对象。

描述

静态方法 Promise.resolve返回一个解析过的Promise对象.

示例

使用静态方法Promise.resolve

Promise.resolve("Success").then(function(value) {
  console.log(value); // "Success"
}, function(value) {
  // 不会被调用
});

对一个数组进行resolve

var p = Promise.resolve([1,2,3]);
p.then(function(v) {
  console.log(v[0]); // 1
});

Resolve另一个promise对象

var original = Promise.resolve('我在第二行');
var cast = Promise.resolve(original);
cast.then(function(value) {
  console.log('value: ' + value);
});
console.log('original === cast ? ' + (original === cast));

/*
*  打印顺序如下，这里有一个同步异步先后执行的区别
*  original === cast ? true
*  value: 我在第二行
*/

resolve thenable的对象们并抛出错误

// Resolve一个thenable对象
var p1 = Promise.resolve({ 
  then: function(onFulfill, onReject) { onFulfill("fulfilled!"); }
});
console.log(p1 instanceof Promise) // true, 这是一个Promise对象

p1.then(function(v) {
    console.log(v); // 输出"fulfilled!"
  }, function(e) {
    // 不会被调用
});

// Thenable在callback之前抛出异常
// Promise rejects
var thenable = { then: function(resolve) {
  throw new TypeError("Throwing");
  resolve("Resolving");
}};

var p2 = Promise.resolve(thenable);
p2.then(function(v) {
  // 不会被调用
}, function(e) {
  console.log(e); // TypeError: Throwing
});

// Thenable在callback之后抛出异常
// Promise resolves
var thenable = { then: function(resolve) {
  resolve("Resolving");
  throw new TypeError("Throwing");
}};

var p3 = Promise.resolve(thenable);
p3.then(function(v) {
  console.log(v); // 输出"Resolving"
}, function(e) {
  // 不会被调用
});

规范

浏览器兼容性

The compatibility table in this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.

参见

• Promise