• Home
  • Line#
  • Scopes#
  • Navigate#
  • Raw
  • Download
1<!DOCTYPE html>
2<html lang="en">
3<head>
4  <meta charset="utf-8">
5  <meta name="viewport" content="width=device-width">
6  <meta name="nodejs.org:node-version" content="v14.20.1">
7  <title>C++ embedder API | Node.js v14.20.1 Documentation</title>
8  <link rel="stylesheet" href="https://fonts.googleapis.com/css?family=Lato:400,700,400italic&display=fallback">
9  <link rel="stylesheet" href="assets/style.css">
10  <link rel="stylesheet" href="assets/hljs.css">
11  <link rel="canonical" href="https://nodejs.org/api/embedding.html">
12</head>
13<body class="alt apidoc" id="api-section-embedding">
14  <div id="content" class="clearfix">
15    <div id="column2" class="interior">
16      <div id="intro" class="interior">
17        <a href="/" title="Go back to the home page">
18          Node.js
19        </a>
20      </div>
21      <ul>
22<li><a href="documentation.html" class="nav-documentation">About this documentation</a></li>
23<li><a href="synopsis.html" class="nav-synopsis">Usage and example</a></li>
24</ul>
25<hr class="line">
26<ul>
27<li><a href="assert.html" class="nav-assert">Assertion testing</a></li>
28<li><a href="async_hooks.html" class="nav-async_hooks">Async hooks</a></li>
29<li><a href="buffer.html" class="nav-buffer">Buffer</a></li>
30<li><a href="addons.html" class="nav-addons">C++ addons</a></li>
31<li><a href="n-api.html" class="nav-n-api">C/C++ addons with Node-API</a></li>
32<li><a href="embedding.html" class="nav-embedding active">C++ embedder API</a></li>
33<li><a href="child_process.html" class="nav-child_process">Child processes</a></li>
34<li><a href="cluster.html" class="nav-cluster">Cluster</a></li>
35<li><a href="cli.html" class="nav-cli">Command-line options</a></li>
36<li><a href="console.html" class="nav-console">Console</a></li>
37<li><a href="corepack.html" class="nav-corepack">Corepack</a></li>
38<li><a href="crypto.html" class="nav-crypto">Crypto</a></li>
39<li><a href="debugger.html" class="nav-debugger">Debugger</a></li>
40<li><a href="deprecations.html" class="nav-deprecations">Deprecated APIs</a></li>
41<li><a href="diagnostics_channel.html" class="nav-diagnostics_channel">Diagnostics Channel</a></li>
42<li><a href="dns.html" class="nav-dns">DNS</a></li>
43<li><a href="domain.html" class="nav-domain">Domain</a></li>
44<li><a href="errors.html" class="nav-errors">Errors</a></li>
45<li><a href="events.html" class="nav-events">Events</a></li>
46<li><a href="fs.html" class="nav-fs">File system</a></li>
47<li><a href="globals.html" class="nav-globals">Globals</a></li>
48<li><a href="http.html" class="nav-http">HTTP</a></li>
49<li><a href="http2.html" class="nav-http2">HTTP/2</a></li>
50<li><a href="https.html" class="nav-https">HTTPS</a></li>
51<li><a href="inspector.html" class="nav-inspector">Inspector</a></li>
52<li><a href="intl.html" class="nav-intl">Internationalization</a></li>
53<li><a href="modules.html" class="nav-modules">Modules: CommonJS modules</a></li>
54<li><a href="esm.html" class="nav-esm">Modules: ECMAScript modules</a></li>
55<li><a href="module.html" class="nav-module">Modules: <code>module</code> API</a></li>
56<li><a href="packages.html" class="nav-packages">Modules: Packages</a></li>
57<li><a href="net.html" class="nav-net">Net</a></li>
58<li><a href="os.html" class="nav-os">OS</a></li>
59<li><a href="path.html" class="nav-path">Path</a></li>
60<li><a href="perf_hooks.html" class="nav-perf_hooks">Performance hooks</a></li>
61<li><a href="policy.html" class="nav-policy">Policies</a></li>
62<li><a href="process.html" class="nav-process">Process</a></li>
63<li><a href="punycode.html" class="nav-punycode">Punycode</a></li>
64<li><a href="querystring.html" class="nav-querystring">Query strings</a></li>
65<li><a href="readline.html" class="nav-readline">Readline</a></li>
66<li><a href="repl.html" class="nav-repl">REPL</a></li>
67<li><a href="report.html" class="nav-report">Report</a></li>
68<li><a href="stream.html" class="nav-stream">Stream</a></li>
69<li><a href="string_decoder.html" class="nav-string_decoder">String decoder</a></li>
70<li><a href="timers.html" class="nav-timers">Timers</a></li>
71<li><a href="tls.html" class="nav-tls">TLS/SSL</a></li>
72<li><a href="tracing.html" class="nav-tracing">Trace events</a></li>
73<li><a href="tty.html" class="nav-tty">TTY</a></li>
74<li><a href="dgram.html" class="nav-dgram">UDP/datagram</a></li>
75<li><a href="url.html" class="nav-url">URL</a></li>
76<li><a href="util.html" class="nav-util">Utilities</a></li>
77<li><a href="v8.html" class="nav-v8">V8</a></li>
78<li><a href="vm.html" class="nav-vm">VM</a></li>
79<li><a href="wasi.html" class="nav-wasi">WASI</a></li>
80<li><a href="worker_threads.html" class="nav-worker_threads">Worker threads</a></li>
81<li><a href="zlib.html" class="nav-zlib">Zlib</a></li>
82</ul>
83<hr class="line">
84<ul>
85<li><a href="https://github.com/nodejs/node" class="nav-https-github-com-nodejs-node">Code repository and issue tracker</a></li>
86</ul>
87    </div>
88
89    <div id="column1" data-id="embedding" class="interior">
90      <header>
91        <div class="header-container">
92          <h1>Node.js v14.20.1 documentation</h1>
93          <button class="theme-toggle-btn" id="theme-toggle-btn" title="Toggle dark mode/light mode" aria-label="Toggle dark mode/light mode" hidden>
94            <svg xmlns="http://www.w3.org/2000/svg" class="icon dark-icon" height="24" width="24">
95              <path fill="none" d="M0 0h24v24H0z" />
96              <path d="M11.1 12.08c-2.33-4.51-.5-8.48.53-10.07C6.27 2.2 1.98 6.59 1.98 12c0 .14.02.28.02.42.62-.27 1.29-.42 2-.42 1.66 0 3.18.83 4.1 2.15A4.01 4.01 0 0111 18c0 1.52-.87 2.83-2.12 3.51.98.32 2.03.5 3.11.5 3.5 0 6.58-1.8 8.37-4.52-2.36.23-6.98-.97-9.26-5.41z"/>
97              <path d="M7 16h-.18C6.4 14.84 5.3 14 4 14c-1.66 0-3 1.34-3 3s1.34 3 3 3h3c1.1 0 2-.9 2-2s-.9-2-2-2z"/>
98            </svg>
99            <svg xmlns="http://www.w3.org/2000/svg" class="icon light-icon" height="24" width="24">
100              <path d="M0 0h24v24H0z" fill="none" />
101              <path d="M6.76 4.84l-1.8-1.79-1.41 1.41 1.79 1.79 1.42-1.41zM4 10.5H1v2h3v-2zm9-9.95h-2V3.5h2V.55zm7.45 3.91l-1.41-1.41-1.79 1.79 1.41 1.41 1.79-1.79zm-3.21 13.7l1.79 1.8 1.41-1.41-1.8-1.79-1.4 1.4zM20 10.5v2h3v-2h-3zm-8-5c-3.31 0-6 2.69-6 6s2.69 6 6 6 6-2.69 6-6-2.69-6-6-6zm-1 16.95h2V19.5h-2v2.95zm-7.45-3.91l1.41 1.41 1.79-1.8-1.41-1.41-1.79 1.8z"/>
102            </svg>
103          </button>
104        </div>
105        <div id="gtoc">
106          <ul>
107            <li>
108              <a href="index.html">Index</a>
109            </li>
110            <li>
111              <a href="all.html">View on single page</a>
112            </li>
113            <li>
114              <a href="embedding.json">View as JSON</a>
115            </li>
116
117    <li class="version-picker">
118      <a href="#">View another version <span>&#x25bc;</span></a>
119      <ol class="version-picker"><li><a href="https://nodejs.org/docs/latest-v18.x/api/embedding.html">18.x</a></li>
120<li><a href="https://nodejs.org/docs/latest-v17.x/api/embedding.html">17.x</a></li>
121<li><a href="https://nodejs.org/docs/latest-v16.x/api/embedding.html">16.x <b>LTS</b></a></li>
122<li><a href="https://nodejs.org/docs/latest-v15.x/api/embedding.html">15.x</a></li>
123<li><a href="https://nodejs.org/docs/latest-v14.x/api/embedding.html">14.x <b>LTS</b></a></li></ol>
124    </li>
125
126            <li class="edit_on_github"><a href="https://github.com/nodejs/node/edit/master/doc/api/embedding.md">Edit on GitHub</a></li>
127          </ul>
128        </div>
129        <hr>
130      </header>
131
132      <details id="toc" open><summary>Table of contents</summary><ul>
133<li><a href="#embedding_c_embedder_api">C++ embedder API</a>
134<ul>
135<li><a href="#embedding_example_embedding_application">Example embedding application</a>
136<ul>
137<li><a href="#embedding_setting_up_per_process_state">Setting up per-process state</a></li>
138<li><a href="#embedding_per_instance_state">Per-instance state</a></li>
139</ul>
140</li>
141</ul>
142</li>
143</ul></details>
144
145      <div id="apicontent">
146        <h2>C++ embedder API<span><a class="mark" href="#embedding_c_embedder_api" id="embedding_c_embedder_api">#</a></span></h2>
147
148<p>Node.js provides a number of C++ APIs that can be used to execute JavaScript
149in a Node.js environment from other C++ software.</p>
150<p>The documentation for these APIs can be found in <a href="https://github.com/nodejs/node/blob/HEAD/src/node.h">src/node.h</a> in the Node.js
151source tree. In addition to the APIs exposed by Node.js, some required concepts
152are provided by the V8 embedder API.</p>
153<p>Because using Node.js as an embedded library is different from writing code
154that is executed by Node.js, breaking changes do not follow typical Node.js
155<a href="deprecations.html">deprecation policy</a> and may occur on each semver-major release without prior
156warning.</p>
157<section><h3>Example embedding application<span><a class="mark" href="#embedding_example_embedding_application" id="embedding_example_embedding_application">#</a></span></h3>
158<p>The following sections will provide an overview over how to use these APIs
159to create an application from scratch that will perform the equivalent of
160<code>node -e &#x3C;code></code>, i.e. that will take a piece of JavaScript and run it in
161a Node.js-specific environment.</p>
162<p>The full code can be found <a href="https://github.com/nodejs/node/blob/HEAD/test/embedding/embedtest.cc">in the Node.js source tree</a>.</p>
163<h4>Setting up per-process state<span><a class="mark" href="#embedding_setting_up_per_process_state" id="embedding_setting_up_per_process_state">#</a></span></h4>
164<p>Node.js requires some per-process state management in order to run:</p>
165<ul>
166<li>Arguments parsing for Node.js <a href="cli.html">CLI options</a>,</li>
167<li>V8 per-process requirements, such as a <code>v8::Platform</code> instance.</li>
168</ul>
169<p>The following example shows how these can be set up. Some class names are from
170the <code>node</code> and <code>v8</code> C++ namespaces, respectively.</p>
171<pre><code class="language-cpp"><span class="hljs-function"><span class="hljs-type">int</span> <span class="hljs-title">main</span><span class="hljs-params">(<span class="hljs-type">int</span> argc, <span class="hljs-type">char</span>** argv)</span> </span>{
172  argv = <span class="hljs-built_in">uv_setup_args</span>(argc, argv);
173  <span class="hljs-function">std::vector&#x3C;std::string> <span class="hljs-title">args</span><span class="hljs-params">(argv, argv + argc)</span></span>;
174  std::vector&#x3C;std::string> exec_args;
175  std::vector&#x3C;std::string> errors;
176  <span class="hljs-comment">// Parse Node.js CLI options, and print any errors that have occurred while</span>
177  <span class="hljs-comment">// trying to parse them.</span>
178  <span class="hljs-type">int</span> exit_code = node::<span class="hljs-built_in">InitializeNodeWithArgs</span>(&#x26;args, &#x26;exec_args, &#x26;errors);
179  <span class="hljs-keyword">for</span> (<span class="hljs-keyword">const</span> std::string&#x26; error : errors)
180    <span class="hljs-built_in">fprintf</span>(stderr, <span class="hljs-string">"%s: %s\n"</span>, args[<span class="hljs-number">0</span>].<span class="hljs-built_in">c_str</span>(), error.<span class="hljs-built_in">c_str</span>());
181  <span class="hljs-keyword">if</span> (exit_code != <span class="hljs-number">0</span>) {
182    <span class="hljs-keyword">return</span> exit_code;
183  }
184
185  <span class="hljs-comment">// Create a v8::Platform instance. `MultiIsolatePlatform::Create()` is a way</span>
186  <span class="hljs-comment">// to create a v8::Platform instance that Node.js can use when creating</span>
187  <span class="hljs-comment">// Worker threads. When no `MultiIsolatePlatform` instance is present,</span>
188  <span class="hljs-comment">// Worker threads are disabled.</span>
189  std::unique_ptr&#x3C;MultiIsolatePlatform> platform =
190      MultiIsolatePlatform::<span class="hljs-built_in">Create</span>(<span class="hljs-number">4</span>);
191  V8::<span class="hljs-built_in">InitializePlatform</span>(platform.<span class="hljs-built_in">get</span>());
192  V8::<span class="hljs-built_in">Initialize</span>();
193
194  <span class="hljs-comment">// See below for the contents of this function.</span>
195  <span class="hljs-type">int</span> ret = <span class="hljs-built_in">RunNodeInstance</span>(platform.<span class="hljs-built_in">get</span>(), args, exec_args);
196
197  V8::<span class="hljs-built_in">Dispose</span>();
198  V8::<span class="hljs-built_in">ShutdownPlatform</span>();
199  <span class="hljs-keyword">return</span> ret;
200}</code></pre>
201<h4>Per-instance state<span><a class="mark" href="#embedding_per_instance_state" id="embedding_per_instance_state">#</a></span></h4>
202<p>Node.js has a concept of a “Node.js instance”, that is commonly being referred
203to as <code>node::Environment</code>. Each <code>node::Environment</code> is associated with:</p>
204<ul>
205<li>Exactly one <code>v8::Isolate</code>, i.e. one JS Engine instance,</li>
206<li>Exactly one <code>uv_loop_t</code>, i.e. one event loop, and</li>
207<li>A number of <code>v8::Context</code>s, but exactly one main <code>v8::Context</code>.</li>
208<li>One <code>node::IsolateData</code> instance that contains information that could be
209shared by multiple <code>node::Environment</code>s that use the same <code>v8::Isolate</code>.
210Currently, no testing if performed for this scenario.</li>
211</ul>
212<p>In order to set up a <code>v8::Isolate</code>, an <code>v8::ArrayBuffer::Allocator</code> needs
213to be provided. One possible choice is the default Node.js allocator, which
214can be created through <code>node::ArrayBufferAllocator::Create()</code>. Using the Node.js
215allocator allows minor performance optimizations when addons use the Node.js
216C++ <code>Buffer</code> API, and is required in order to track <code>ArrayBuffer</code> memory in
217<a href="process.html#process_process_memoryusage"><code>process.memoryUsage()</code></a>.</p>
218<p>Additionally, each <code>v8::Isolate</code> that is used for a Node.js instance needs to
219be registered and unregistered with the <code>MultiIsolatePlatform</code> instance, if one
220is being used, in order for the platform to know which event loop to use
221for tasks scheduled by the <code>v8::Isolate</code>.</p>
222<p>The <code>node::NewIsolate()</code> helper function creates a <code>v8::Isolate</code>,
223sets it up with some Node.js-specific hooks (e.g. the Node.js error handler),
224and registers it with the platform automatically.</p>
225<pre><code class="language-cpp"><span class="hljs-function"><span class="hljs-type">int</span> <span class="hljs-title">RunNodeInstance</span><span class="hljs-params">(MultiIsolatePlatform* platform,
226                    <span class="hljs-keyword">const</span> std::vector&#x3C;std::string>&#x26; args,
227                    <span class="hljs-keyword">const</span> std::vector&#x3C;std::string>&#x26; exec_args)</span> </span>{
228  <span class="hljs-type">int</span> exit_code = <span class="hljs-number">0</span>;
229  <span class="hljs-comment">// Set up a libuv event loop.</span>
230  <span class="hljs-type">uv_loop_t</span> loop;
231  <span class="hljs-type">int</span> ret = <span class="hljs-built_in">uv_loop_init</span>(&#x26;loop);
232  <span class="hljs-keyword">if</span> (ret != <span class="hljs-number">0</span>) {
233    <span class="hljs-built_in">fprintf</span>(stderr, <span class="hljs-string">"%s: Failed to initialize loop: %s\n"</span>,
234            args[<span class="hljs-number">0</span>].<span class="hljs-built_in">c_str</span>(),
235            <span class="hljs-built_in">uv_err_name</span>(ret));
236    <span class="hljs-keyword">return</span> <span class="hljs-number">1</span>;
237  }
238
239  std::shared_ptr&#x3C;ArrayBufferAllocator> allocator =
240      ArrayBufferAllocator::<span class="hljs-built_in">Create</span>();
241
242  Isolate* isolate = <span class="hljs-built_in">NewIsolate</span>(allocator, &#x26;loop, platform);
243  <span class="hljs-keyword">if</span> (isolate == <span class="hljs-literal">nullptr</span>) {
244    <span class="hljs-built_in">fprintf</span>(stderr, <span class="hljs-string">"%s: Failed to initialize V8 Isolate\n"</span>, args[<span class="hljs-number">0</span>].<span class="hljs-built_in">c_str</span>());
245    <span class="hljs-keyword">return</span> <span class="hljs-number">1</span>;
246  }
247
248  {
249    <span class="hljs-function">Locker <span class="hljs-title">locker</span><span class="hljs-params">(isolate)</span></span>;
250    <span class="hljs-function">Isolate::Scope <span class="hljs-title">isolate_scope</span><span class="hljs-params">(isolate)</span></span>;
251
252    <span class="hljs-comment">// Create a node::IsolateData instance that will later be released using</span>
253    <span class="hljs-comment">// node::FreeIsolateData().</span>
254    <span class="hljs-function">std::unique_ptr&#x3C;IsolateData, <span class="hljs-title">decltype</span><span class="hljs-params">(&#x26;node::FreeIsolateData)</span>> <span class="hljs-title">isolate_data</span><span class="hljs-params">(
255        node::CreateIsolateData(isolate, &#x26;loop, platform, allocator.get()),
256        node::FreeIsolateData)</span></span>;
257
258    <span class="hljs-comment">// Set up a new v8::Context.</span>
259    <span class="hljs-function">HandleScope <span class="hljs-title">handle_scope</span><span class="hljs-params">(isolate)</span></span>;
260    Local&#x3C;Context> context = node::<span class="hljs-built_in">NewContext</span>(isolate);
261    <span class="hljs-keyword">if</span> (context.<span class="hljs-built_in">IsEmpty</span>()) {
262      <span class="hljs-built_in">fprintf</span>(stderr, <span class="hljs-string">"%s: Failed to initialize V8 Context\n"</span>, args[<span class="hljs-number">0</span>].<span class="hljs-built_in">c_str</span>());
263      <span class="hljs-keyword">return</span> <span class="hljs-number">1</span>;
264    }
265
266    <span class="hljs-comment">// The v8::Context needs to be entered when node::CreateEnvironment() and</span>
267    <span class="hljs-comment">// node::LoadEnvironment() are being called.</span>
268    <span class="hljs-function">Context::Scope <span class="hljs-title">context_scope</span><span class="hljs-params">(context)</span></span>;
269
270    <span class="hljs-comment">// Create a node::Environment instance that will later be released using</span>
271    <span class="hljs-comment">// node::FreeEnvironment().</span>
272    <span class="hljs-function">std::unique_ptr&#x3C;Environment, <span class="hljs-title">decltype</span><span class="hljs-params">(&#x26;node::FreeEnvironment)</span>> <span class="hljs-title">env</span><span class="hljs-params">(
273        node::CreateEnvironment(isolate_data.get(), context, args, exec_args),
274        node::FreeEnvironment)</span></span>;
275
276    <span class="hljs-comment">// Set up the Node.js instance for execution, and run code inside of it.</span>
277    <span class="hljs-comment">// There is also a variant that takes a callback and provides it with</span>
278    <span class="hljs-comment">// the `require` and `process` objects, so that it can manually compile</span>
279    <span class="hljs-comment">// and run scripts as needed.</span>
280    <span class="hljs-comment">// The `require` function inside this script does *not* access the file</span>
281    <span class="hljs-comment">// system, and can only load built-in Node.js modules.</span>
282    <span class="hljs-comment">// `module.createRequire()` is being used to create one that is able to</span>
283    <span class="hljs-comment">// load files from the disk, and uses the standard CommonJS file loader</span>
284    <span class="hljs-comment">// instead of the internal-only `require` function.</span>
285    MaybeLocal&#x3C;Value> loadenv_ret = node::<span class="hljs-built_in">LoadEnvironment</span>(
286        env.<span class="hljs-built_in">get</span>(),
287        <span class="hljs-string">"const publicRequire ="</span>
288        <span class="hljs-string">"  require('module').createRequire(process.cwd() + '/');"</span>
289        <span class="hljs-string">"globalThis.require = publicRequire;"</span>
290        <span class="hljs-string">"require('vm').runInThisContext(process.argv[1]);"</span>);
291
292    <span class="hljs-keyword">if</span> (loadenv_ret.<span class="hljs-built_in">IsEmpty</span>())  <span class="hljs-comment">// There has been a JS exception.</span>
293      <span class="hljs-keyword">return</span> <span class="hljs-number">1</span>;
294
295    {
296      <span class="hljs-comment">// SealHandleScope protects against handle leaks from callbacks.</span>
297      <span class="hljs-function">SealHandleScope <span class="hljs-title">seal</span><span class="hljs-params">(isolate)</span></span>;
298      <span class="hljs-type">bool</span> more;
299      <span class="hljs-keyword">do</span> {
300        <span class="hljs-built_in">uv_run</span>(&#x26;loop, UV_RUN_DEFAULT);
301
302        <span class="hljs-comment">// V8 tasks on background threads may end up scheduling new tasks in the</span>
303        <span class="hljs-comment">// foreground, which in turn can keep the event loop going. For example,</span>
304        <span class="hljs-comment">// WebAssembly.compile() may do so.</span>
305        platform-><span class="hljs-built_in">DrainTasks</span>(isolate);
306
307        <span class="hljs-comment">// If there are new tasks, continue.</span>
308        more = <span class="hljs-built_in">uv_loop_alive</span>(&#x26;loop);
309        <span class="hljs-keyword">if</span> (more) <span class="hljs-keyword">continue</span>;
310
311        <span class="hljs-comment">// node::EmitProcessBeforeExit() is used to emit the 'beforeExit' event</span>
312        <span class="hljs-comment">// on the `process` object.</span>
313        <span class="hljs-keyword">if</span> (node::<span class="hljs-built_in">EmitProcessBeforeExit</span>(env.<span class="hljs-built_in">get</span>()).<span class="hljs-built_in">IsNothing</span>())
314          <span class="hljs-keyword">break</span>;
315
316        <span class="hljs-comment">// 'beforeExit' can also schedule new work that keeps the event loop</span>
317        <span class="hljs-comment">// running.</span>
318        more = <span class="hljs-built_in">uv_loop_alive</span>(&#x26;loop);
319      } <span class="hljs-keyword">while</span> (more == <span class="hljs-literal">true</span>);
320    }
321
322    <span class="hljs-comment">// node::EmitProcessExit() returns the current exit code.</span>
323    exit_code = node::<span class="hljs-built_in">EmitProcessExit</span>(env.<span class="hljs-built_in">get</span>()).<span class="hljs-built_in">FromMaybe</span>(<span class="hljs-number">1</span>);
324
325    <span class="hljs-comment">// node::Stop() can be used to explicitly stop the event loop and keep</span>
326    <span class="hljs-comment">// further JavaScript from running. It can be called from any thread,</span>
327    <span class="hljs-comment">// and will act like worker.terminate() if called from another thread.</span>
328    node::<span class="hljs-built_in">Stop</span>(env.<span class="hljs-built_in">get</span>());
329  }
330
331  <span class="hljs-comment">// Unregister the Isolate with the platform and add a listener that is called</span>
332  <span class="hljs-comment">// when the Platform is done cleaning up any state it had associated with</span>
333  <span class="hljs-comment">// the Isolate.</span>
334  <span class="hljs-type">bool</span> platform_finished = <span class="hljs-literal">false</span>;
335  platform-><span class="hljs-built_in">AddIsolateFinishedCallback</span>(isolate, [](<span class="hljs-type">void</span>* data) {
336    *<span class="hljs-built_in">static_cast</span>&#x3C;<span class="hljs-type">bool</span>*>(data) = <span class="hljs-literal">true</span>;
337  }, &#x26;platform_finished);
338  platform-><span class="hljs-built_in">UnregisterIsolate</span>(isolate);
339  isolate-><span class="hljs-built_in">Dispose</span>();
340
341  <span class="hljs-comment">// Wait until the platform has cleaned up all relevant resources.</span>
342  <span class="hljs-keyword">while</span> (!platform_finished)
343    <span class="hljs-built_in">uv_run</span>(&#x26;loop, UV_RUN_ONCE);
344  <span class="hljs-type">int</span> err = <span class="hljs-built_in">uv_loop_close</span>(&#x26;loop);
345  <span class="hljs-built_in">assert</span>(err == <span class="hljs-number">0</span>);
346
347  <span class="hljs-keyword">return</span> exit_code;
348}</code></pre></section>
349        <!-- API END -->
350      </div>
351    </div>
352  </div>
353  <script>
354    'use strict';
355    {
356      const kCustomPreference = 'customDarkTheme';
357      const userSettings = sessionStorage.getItem(kCustomPreference);
358      const themeToggleButton = document.getElementById('theme-toggle-btn');
359      if (userSettings === null && window.matchMedia) {
360        const mq = window.matchMedia('(prefers-color-scheme: dark)');
361        if ('onchange' in mq) {
362          function mqChangeListener(e) {
363            document.body.classList.toggle('dark-mode', e.matches);
364          }
365          mq.addEventListener('change', mqChangeListener);
366          if (themeToggleButton) {
367            themeToggleButton.addEventListener('click', function() {
368              mq.removeEventListener('change', mqChangeListener);
369            }, { once: true });
370          }
371        }
372        if (mq.matches) {
373          document.body.classList.add('dark-mode');
374        }
375      } else if (userSettings === 'true') {
376        document.body.classList.add('dark-mode');
377      }
378      if (themeToggleButton) {
379        themeToggleButton.hidden = false;
380        themeToggleButton.addEventListener('click', function() {
381          sessionStorage.setItem(
382            kCustomPreference,
383            document.body.classList.toggle('dark-mode')
384          );
385        });
386      }
387    }
388  </script>
389</body>
390</html>
391