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---
title: Promise.resolve()
slug: Web/JavaScript/Reference/Global_Objects/Promise/resolve
tags:
- ECMAScript 2015
- JavaScript
- Promise
translation_of: Web/JavaScript/Reference/Global_Objects/Promise/resolve
---
<div>{{JSRef}}</div>
<div><code><strong>Promise.resolve(value)</strong></code>方法返回一个以给定值解析后的{{jsxref("Promise")}} 对象。如果这个值是一个 promise ，那么将返回这个 promise ；如果这个值是thenable（即带有{{jsxref("Promise.then", "\"then\" ")}}方法），返回的promise会“跟随”这个thenable的对象，采用它的最终状态；否则返回的promise将以此值完成。<span style="font-size: 1rem; letter-spacing: -0.00278rem;">此函数将类promise对象的多层嵌套展平。</span></div>
<div></div>
<div></div>
<div class="blockIndicator warning">
<p>警告：不要在解析为自身的thenable 上调用<code>Promise.resolve</code>。这将导致无限递归，因为它试图展平无限嵌套的promise。一个例子是将它与Angular中的异步管道一起使用。在<a href="https://angular.io/guide/template-syntax#avoid-side-effects">此处</a>了解更多信息。</p>
</div>
<div>例如下例代码</div>
<pre class="brush: js">
let thenable = {
then: (resolve, reject) => {
resolve(thenable)
}
}
Promise.resolve(thenable) //这会造成一个死循环
</pre>
<div>{{EmbedInteractiveExample("pages/js/promise-resolve.html")}}</div>
<p class="hidden">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 <a href="https://github.com/mdn/interactive-examples">https://github.com/mdn/interactive-examples</a> and send us a pull request.</p>
<h2 id="Syntax" name="Syntax">语法</h2>
<pre class="syntaxbox"><var>Promise.resolve(value)</var>;
</pre>
<h3 id="参数">参数</h3>
<dl>
<dt>value</dt>
</dl>
<p>将被<code>Promise</code>对象解析的参数，也可以是一个<code>Promise</code>对象，或者是一个thenable。</p>
<h3 id="返回值">返回值</h3>
<p>返回一个带着给定值解析过的<code>Promise</code>对象，如果参数本身就是一个<code>Promise</code>对象，则直接返回这个<code>Promise</code>对象。</p>
<h2 id="Description" name="Description">描述</h2>
<p>静态方法 <code>Promise.resolve</code>返回一个解析过的<code>Promise</code>对象。</p>
<h2 id="示例">示例</h2>
<h3 id="使用静态Promise.resolve方法">使用静态<code>Promise.resolve</code>方法</h3>
<pre class="brush: js">Promise.resolve("Success").then(function(value) {
console.log(value); // "Success"
}, function(value) {
// 不会被调用
});
</pre>
<h3 id="resolve一个数组">resolve一个数组</h3>
<pre class="brush: js">var p = Promise.resolve([1,2,3]);
p.then(function(v) {
console.log(v[0]); // 1
});
</pre>
<h3 id="resolve另一个promise">resolve另一个promise</h3>
<pre class="brush: js">var original = Promise.resolve(33);
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: 33
*/</pre>
<p>日志顺序颠倒其实是由于异步地调用<code>then</code> 方法。在<a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise/then#Return_value">这里</a>查看<code>then</code> 是如何工作的。</p>
<h3 id="resolve_thenable_并抛出错误">resolve thenable 并抛出错误</h3>
<pre class="brush: js">// 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
});
</pre>
<h2 id="规范">规范</h2>
<table class="standard-table">
<tbody>
<tr>
<th scope="col">Specification</th>
<th scope="col">Status</th>
<th scope="col">Comment</th>
</tr>
<tr>
<td>{{SpecName('ES6', '#sec-promise.resolve', 'Promise.resolve')}}</td>
<td>{{Spec2('ES6')}}</td>
<td>ECMA标准中的首次定义</td>
</tr>
<tr>
<td>{{SpecName('ESDraft', '#sec-promise.resolve', 'Promise.resolve')}}</td>
<td>{{Spec2('ES6')}}</td>
<td></td>
</tr>
</tbody>
</table>
<h2 id="浏览器兼容性">浏览器兼容性</h2>
<p>{{Compat("javascript.builtins.Promise.resolve")}}</p>
<h2 id="参见">参见</h2>
<ul>
<li>{{jsxref("Promise")}}</li>
</ul>
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