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---
title: Promise.resolve()
slug: Web/JavaScript/Reference/Global_Objects/Promise/resolve
translation_of: Web/JavaScript/Reference/Global_Objects/Promise/resolve
---
<div>{{JSRef}}</div>
<p><code><strong>Promise.resolve(value)</strong></code> 方法回傳一個以 value 判定結果的 {{jsxref("Promise")}} 物件。若 value 是個 thenable (例如，具有 {{jsxref("Promise.then", "\"then\"方法")}})，則回傳的 promise 將依其結果採取其最終狀態；若 value 是 promise，則作為呼叫 Promise.resolve 之結果；其他情形都將回傳以 value 實現的 promise。</p>
<h2 id="語法">語法</h2>
<pre class="brush: js">Promise.resolve(value);
Promise.resolve(promise);
Promise.resolve(thenable);
</pre>
<h3 id="參數">參數</h3>
<dl>
<dt>value</dt>
<dd>將被 <code>Promise</code> 實現的引數（argument）。可以是個 <code>Promise</code> 或待解決的 thenable。</dd>
</dl>
<h3 id="回傳值">回傳值</h3>
<p>以 value 或作為 value 的 promise 解決的 {{jsxref("Promise")}}。</p>
<h2 id="描述">描述</h2>
<p><code>靜態函式</code> <code>Promise.resolve</code> 回傳判定後的 <code>Promise。</code></p>
<h2 id="範例">範例</h2>
<h3 id="使用_Promise.resolve_靜態方法">使用 <code>Promise.resolve</code> 靜態方法</h3>
<pre class="brush: js">Promise.resolve('Success').then(function(value) {
console.log(value); // "Success"
}, function(value) {
// not called
});
</pre>
<h3 id="判定陣列">判定陣列</h3>
<pre class="brush: js">var p = Promise.resolve([1,2,3]);
p.then(function(v) {
console.log(v[0]); // 1
});
</pre>
<h3 id="判定另一個_Promise">判定另一個 <code>Promise</code></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));
// logs, in order:
// original === cast ? true
// value: 33
</pre>
<p>由於 handlers 是非同步地被調用而導致相反的紀錄順序。經由<a href="https://developer.mozilla.org/zh-TW/docs/Web/JavaScript/Reference/Global_Objects/Promise/then#回傳值">這篇文章</a>了解 then 如何運作。</p>
<h3 id="判定_thenables_及拋出_Errors">判定 thenables 及拋出 Errors</h3>
<pre class="brush: js">// Resolving a thenable object
var p1 = Promise.resolve({
then: function(onFulfill, onReject) { onFulfill('fulfilled!'); }
});
console.log(p1 instanceof Promise) // true, object casted to a Promise
p1.then(function(v) {
console.log(v); // "fulfilled!"
}, function(e) {
// not called
});
// Thenable throws before callback
// Promise rejects
var thenable = { then: function(resolve) {
throw new TypeError('Throwing');
resolve('Resolving');
}};
var p2 = Promise.resolve(thenable);
p2.then(function(v) {
// not called
}, function(e) {
console.log(e); // TypeError: Throwing
});
// Thenable throws after callback
// 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); // "Resolving"
}, function(e) {
// not called
});
</pre>
<h2 id="規範">規範</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('ES2015', '#sec-promise.resolve', 'Promise.resolve')}}</td>
<td>{{Spec2('ES2015')}}</td>
<td>Initial definition in an ECMA standard.</td>
</tr>
<tr>
<td>{{SpecName('ESDraft', '#sec-promise.resolve', 'Promise.resolve')}}</td>
<td>{{Spec2('ESDraft')}}</td>
<td> </td>
</tr>
</tbody>
</table>
<h2 id="瀏覽器相容性">瀏覽器相容性</h2>
<p>{{Compat("javascript.builtins.Promise.resolve")}}</p>
<h2 id="參見">參見</h2>
<ul>
<li>{{jsxref("Promise")}}</li>
</ul>
|
