JS_NewExternalString

  • Revision slug: SpiderMonkey/JSAPI_Reference/JS_NewExternalString
  • Revision title: JS_NewExternalString
  • Revision id: 88533
  • Created:
  • Creator: Jorend
  • Is current revision? No
  • Comment no wording changes; page display name changed to 'JS_NewExternalString'

Revision Content

{{ Jsapi_ref_header("JS_NewExternalString") }}

Creates a new JSString whose characters are stored in external memory, i.e., memory allocated by the application, not the JavaScript engine. Since the program allocated the memory, it will need to free it; this happens in an external string finalizer indicated by the type parameter.

Syntax

JSString * JS_NewExternalString(JSContext *cx, jschar *chars, size_t length, intN type);
Name Type Description
cx JSContext * The context in which to create the new string. {{ Jsapi-requires-request() }}
chars jschar * Pointer to an array of jschars. This array is used as the character buffer of the JSString to be created. The array must be populated with the desired character data before JS_NewExternalString is called, and the array must remain in memory, with its contents unchanged, for as long as the JavaScript engine needs to hold on to it. (Ultimately, the string will be garbage collected, and the JavaScript engine will call the string finalizer callback, allowing the application to free the array.) The array does not need to be zero-terminated.
length size_t The number of characters in the array chars.
type intN Indicates which string finalizer callback the JavaScript engine should use (later) to free the string buffer chars. This must be an id number previously returned by a successful call to JS_AddExternalStringFinalizer.

{{ LXRSearch("ident", "i", "JS_NewExternalString") }}

Revision Source

<p>{{ Jsapi_ref_header("JS_NewExternalString") }}
</p><p>Creates a new <code><a href="/en/JSString" title="en/JSString">JSString</a></code> whose characters are stored in external memory, i.e., memory allocated by the application, not the JavaScript engine. Since the program allocated the memory, it will need to free it; this happens in an <em>external string finalizer</em> indicated by the <code>type</code> parameter.
</p>
<h2 name="Syntax"> Syntax </h2>
<pre class="eval"><a href="/en/JSString" title="en/JSString">JSString</a> * <strong>JS_NewExternalString</strong>(<a href="/en/JSRuntime" title="en/JSRuntime">JSContext</a> *cx, <a href="/en/jschar" title="en/jschar">jschar</a> *chars, size_t length, <a href="/en/jsint" title="en/jsint">intN</a> type);
</pre>
<table class="fullwidth-table">
<tbody><tr>
<th>Name</th>
<th>Type</th>
<th>Description</th>
</tr>
<tr>
<td><code>cx</code></td>
<td><code><a href="/en/JSRuntime" title="en/JSRuntime">JSContext</a> *</code></td>
<td>The context in which to create the new string.
{{ Jsapi-requires-request() }}</td>
</tr>
<tr>
<td><code>chars</code></td>
<td><code><a href="/en/jschar" title="en/jschar">jschar</a> *</code></td>
<td>Pointer to an array of <code>jschar</code>s. This array is used as the character buffer of the <code>JSString</code> to be created. The array must be populated with the desired character data before <code>JS_NewExternalString</code> is called, and the array must remain in memory, with its contents unchanged, for as long as the JavaScript engine needs to hold on to it. (Ultimately, the string will be garbage collected, and the JavaScript engine will call the string finalizer callback, allowing the application to free the array.)
The array does not need to be zero-terminated.</td>
</tr><tr>
<td><code>length</code></td>
<td><code>size_t</code></td>
<td>The number of characters in the array <code>chars</code>.</td>
</tr>
<tr>
<td><code>type</code></td>
<td><code><a href="/en/jsint" title="en/jsint">intN</a></code></td>
<td>Indicates which string finalizer callback the JavaScript engine should use (later) to free the string buffer <code>chars</code>. This must be an id number previously returned by a successful call to <code><a href="/en/JS_AddExternalStringFinalizer" title="en/JS_AddExternalStringFinalizer">JS_AddExternalStringFinalizer</a></code>.</td>
</tr>
</tbody></table>
<p>{{ LXRSearch("ident", "i", "JS_NewExternalString") }}
</p>
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