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[WIP] WebAssembly JavaScript Module integration
For concreteness, this patch specifies how the WebAssembly JavaScript module integration proposal [1] could work in HTML. It is not yet ready to merge, as the proposal is still in a relatively early state. Note that this change depends on the ability for modules to block in the evaluation phase, to permit WebAssembly module instantiation to yield, as is necessary on some platforms where compilation work is performed during the first instantiation. Such an ability to yield is provided by the JavaScript top-level await proposal [2] and associated HTML integration patch whatwg#4352. [1] https://github.com/webassembly/esm-integration [2] https://github.com/tc39/proposal-top-level-await
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@@ -2493,6 +2493,7 @@ a.setAttribute('href', 'https://example.com/'); // change the content attribute
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<li><dfn data-x="body safely extract" data-x-href="https://fetch.spec.whatwg.org/#bodyinit-safely-extract">safely extracting a body</dfn></li>
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<li><dfn data-x-href="https://fetch.spec.whatwg.org/#process-response-end-of-body">processResponseConsumeBody</dfn></li>
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<li><dfn data-x-href="https://fetch.spec.whatwg.org/#fetch-processresponseendofbody">processResponseEndOfBody</dfn></li>
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<li><dfn data-x-href="https://fetch.spec.whatwg.org/#concept-body-consume-body">consume body</dfn></li>
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<li>
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<dfn data-x="concept-response"
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data-x-href="https://fetch.spec.whatwg.org/#concept-response">response</dfn> and its
@@ -4186,6 +4187,19 @@ a.setAttribute('href', 'https://example.com/'); // change the content attribute
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<ul class="brief">
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<li><dfn data-x-href="https://wicg.github.io/uuid/#dfn-generate-a-random-uuid">generating a random UUID</dfn></li>
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</ul>
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</dd>
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<dt>WebAssembly JavaScript Module Integration</dt>
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<dd>
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<p>The following terms are defined in <cite>WebAssembly JavaScript Module Integration</cite>: <ref spec=WASMESM></p>
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<ul class="brief">
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<li><dfn data-x-href="https://webassembly.github.io/esm-integration/js-api/index.html#webassembly-module-record">WebAssembly Module Record</dfn></li>
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<li><dfn data-x-href="https://webassembly.github.io/esm-integration/js-api/index.html#parse-a-webassembly-module">parse a WebAssembly module</dfn></li>
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</ul>
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</dd>
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</dl>
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<hr>
@@ -91620,6 +91634,9 @@ document.querySelector("button").addEventListener("click", bound);
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<li><p>a <span>Synthetic Module Record</span>, for <span data-x="CSS module script">CSS module
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scripts</span> and <span data-x="JSON module script">JSON module scripts</span></p></li>
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<li><p>a <span>WebAssembly Module Record</span>, for <span data-x="WebAssembly module
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script">WebAssembly module scripts</span>;</p></li>
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<li><p>null, representing a parsing failure.</p></li>
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</ul>
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</dd>
@@ -91691,6 +91708,10 @@ document.querySelector("button").addEventListener("click", bound);
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its <span data-x="concept-script-record">record</span> is a <span>Source Text Module
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Record</span>.</p></li>
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<li><p>A <span>module script</span> is a <dfn data-export="">WebAssembly module script</dfn> if
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its <span data-x="concept-script-record">record</span> is a <span>WebAssembly Module
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Record</span>.</p></li>
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<li>
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<p>A <span>module script</span> is a <dfn data-export="">CSS module script</dfn> if its <span
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data-x="concept-script-record">record</span> is a <span>Synthetic Module Record</span>, and it
@@ -92705,6 +92726,22 @@ document.querySelector("button").addEventListener("click", bound);
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<span>creating a JSON module script</span> given <var>source text</var> and <var>module map
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settings object</var>.</p></li>
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<li><p>If the <span>MIME type essence</span> of <var>MIME type</var> is
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"<code>application/wasm</code>" and <var>module type</var> is "<code
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data-x="">javascript</code>", then:</p>
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<ol>
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<li><p>Let <var>bufferPromise</var> be the result of running <span>consume body</span> on
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<var>response</var> with <i>ArrayBuffer</i>.</p></li>
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<li><p><span data-x="creating a WebAssembly module script">Create a WebAssembly module
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script</span> given <var>bufferPromise</var>, <var>module map settings object</var>,
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<var>response</var>'s <span data-x="concept-response-url">url</span>, and <var>options</var>.
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Wait until the algorithm asynchronously completes with <var>result</var>.</p></li>
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<li><p>Set <var>module script</var> to <var>result</var>.</p></li>
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</ol>
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</li>
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<li>
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<p><span data-x="map set">Set</span> <var>moduleMap</var>[(<var>url</var>,
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<var>moduleType</var>)] to <var>module script</var>, and asynchronously complete this algorithm
@@ -92890,36 +92927,12 @@ document.querySelector("button").addEventListener("click", bound);
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we only asked for "<code data-x="">type</code>" assertions in
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<span>HostGetSupportedImportAssertions</span>.</p></li>
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<li id="validate-requested-module-specifiers">
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<p><span data-x="list iterate">For each</span> <span>ModuleRequest record</span>
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<var>requested</var> of <var>result</var>.[[RequestedModules]]:</p>
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<ol>
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<li><p>Let <var>url</var> be the result of <span data-x="resolve a module specifier">resolving
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a module specifier</span> given <var>script</var>'s <span data-x="concept-script-base-url">base
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URL</span> and <var>requested</var>.[[Specifier]].</p></li>
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<li><p>Let <var>moduleType</var> be the result of running the <span>module type from module
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request</span> steps given <var>requested</var>.</p></li>
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<li><p>Run the <span>validate requested module specifiers</span> steps given <var>result</var>
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and <var>script</var>.</p>
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<li>
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<p>If <var>url</var> is failure, or if the result of running the <span>module type
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allowed</span> steps given <var>moduleType</var> and <var>settings</var> is false, then:</p>
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<ol>
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<li><p>Let <var>error</var> be a new <code>TypeError</code> exception.</p></li>
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<li><p>Set <var>script</var>'s <span data-x="concept-script-parse-error">parse error</span>
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to <var>error</var>.</p></li>
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<li><p>Return <var>script</var>.</p></li>
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</ol>
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</li>
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</ol>
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<p class="note">This step is essentially validating all of the requested module specifiers and
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type assertions. We treat a module with unresolvable module specifiers or unsupported type
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assertions the same as one that cannot be parsed; in both cases, a syntactic issue makes it
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impossible to ever contemplate linking the module later.</p>
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<p>If these steps throw an exception, set <var>script</var>'s <span
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data-x="concept-script-parse-error">parse error</span> to that exception, and return
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<var>script</var>.</p>
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</li>
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<li><p>Set <var>script</var>'s <span data-x="concept-script-record">record</span> to
@@ -92996,6 +93009,109 @@ document.querySelector("button").addEventListener("click", bound);
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<li><p>Return <var>script</var>.</p></li>
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</ol>
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<p>To <dfn data-x="creating a WebAssembly module script">create a WebAssembly module script</dfn>,
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given a promise that will resolve with an <code data-x="idl-ArrayBuffer">ArrayBuffer</code>
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<var>bufferPromise</var>, an <span>environment settings object</span> <var>settings</var>, a
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<span>URL</span> <var>baseURL</var>, and some <span>script fetch options</span>
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<var>options</var>, run these steps. The algorithm will asynchronously complete with a new
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<span>WebAssembly module script</span>.</p>
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<ol>
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<li><p>If <span data-x="concept-environment-noscript">scripting is disabled</span> for
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<var>settings</var>, then set <var>bufferPromise</var> to a promise resolved with an empty
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<code data-x="idl-ArrayBuffer">ArrayBuffer</code>.</p></li>
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<!-- REVIEW NOTE: this will cause a parse error, because it doesn't have the magic bytes. -->
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<li><p>Let <var>script</var> be a new <span>WebAssembly module script</span> that this algorithm
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will subsequently initialize.</p></li>
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<li><p>Set <var>script</var>'s <span>settings object</span> to <var>settings</var>.</p></li>
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<li><p>Set <var>script</var>'s <span data-x="concept-script-base-url">base URL</span> to
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<var>baseURL</var>.</p></li>
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<li><p>Set <var>script</var>'s <span data-x="concept-script-script-fetch-options">fetch
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options</span> to <var>options</var>.</p></li>
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<li><p>Set <var>script</var>'s <span data-x="concept-script-parse-error">parse error</span> and
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<span data-x="concept-script-error-to-rethrow">error to rethrow</span> to null.</p></li>
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<li>
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<p>Upon fulfillment of <var>bufferPromise</var> with <var>buffer</var>:</p>
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<ol>
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<li>
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<p>Let <var>module</var> be the result of <span>parse a WebAssembly module</span> given
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<var>buffer</var>, <var>settings</var>'s <span data-x="environment settings object's
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Realm">Realm</span>, and <var>script</var>.</p>
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<p class="note">Passing <var>script</var> as the last parameter here ensures
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<var>result</var>.[[HostDefined]] will be <var>script</var>.</p>
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<p>If this algorithm throws an exception, set <var>script</var>'s <span
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data-x="concept-script-parse-error">parse error</span> to that exception, and asynchronously
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complete this algorithm with <var>script</var>.</p>
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</li>
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<li><p>Run the <span>validate requested module specifiers</span> steps given <var>module</var>
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and <var>script</var>.</p>
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</li>
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<li><p>Set <var>script</var>'s <span data-x="concept-script-record">record</span> to
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<var>module</var>.</p></li>
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<li><p>Asynchronously complete this algorithm with <var>script</var>.</p></li>
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</ol>
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</li>
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<li>
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<p>Upon rejection of <var>bufferPromise</var> with <var>reason</var>:</p>
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<ol>
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<li><p>Set <var>script</var>'s <span data-x="concept-script-parse-error">parse error</span> to
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<var>reason</var>.</p></li>
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<li><p>Asynchronously complete this algorithm with <var>script</var>.</p></li>
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</ol>
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</li>
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</ol>
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<p>The <dfn id="validate-requested-module-specifiers">validate requested module specifiers</dfn>
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steps, given a module record <var>record</var> and a script <var>script</var>, are as
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follows:</p>
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<ol>
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<li>
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<p><span data-x="list iterate">For each</span> <span>ModuleRequest record</span>
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<var>requested</var> of <var>record</var>.[[RequestedModules]]:</p>
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<ol>
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<li><p>Let <var>url</var> be the result of <span data-x="resolve a module specifier">resolving
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a module specifier</span> given <var>script</var>'s <span data-x="concept-script-base-url">base
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URL</span> and <var>requested</var>.[[Specifier]].</p></li>
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<li><p>Let <var>moduleType</var> be the result of running the <span>module type from module
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request</span> steps given <var>requested</var>.</p></li>
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<li>
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<p>If <var>url</var> is failure, or if the result of running the <span>module type
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allowed</span> steps given <var>moduleType</var> and <var>settings</var> is false, then:</p>
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<ol>
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<li><p>Let <var>error</var> be a new <code>TypeError</code> exception.</p></li>
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<li><p>Throw <var>error</var>.</p></li>
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</ol>
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</li>
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</ol>
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</li>
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</ol>
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<p class="note">These steps are essentially validating all of the requested module specifiers and
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type assertions. We treat a module with unresolvable module specifiers or unsupported type
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assertions the same as one that cannot be parsed; in both cases, a syntactic issue makes it
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impossible to ever contemplate linking the module later.</p>
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<p>The <dfn>module type from module request</dfn> steps, given a <span>ModuleRequest
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Record</span> <var>moduleRequest</var>, are as follows:</p>
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@@ -126668,6 +126784,9 @@ INSERT INTERFACES HERE
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<dt><dfn><code>application/xml</code></dfn></dt>
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<dd>XML <ref spec=XML> <ref spec=RFC7303></dd>
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<dt><dfn><code>application/wasm</code></dfn></dt>
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<dd>WebAssembly <ref spec=WASM></dd>
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<dt><dfn><code>image/gif</code></dfn></dt>
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<dd>GIF images <ref spec=GIF></dd>
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@@ -127314,6 +127433,12 @@ INSERT INTERFACES HERE
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<dt id="refsWASMJS">[WASMJS]</dt>
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<dd>(Non-normative) <cite><a href="https://webassembly.github.io/spec/js-api/">WebAssembly JavaScript Interface</a></cite>, D. Ehrenberg. W3C.</dd>
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<dt id="refsWASM">[WASM]</dt>
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<dd><cite><a href="https://webassembly.github.io/spec/core/bikeshed/index.html">WebAssembly Core Specification</a></cite>, A. Rossberg. W3C.</dd>
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<dt id="refsWASMESM">[WASMESM]</dt>
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<dd><cite><a href="https://webassembly.github.io/esm-integration/js-api/index.html">WebAssembly JavaScript Module Integration</a></cite>, L. Clark, D. Ehrenberg. W3C.</dd>
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<dt id="refsWCAG">[WCAG]</dt>
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<dd>(Non-normative) <cite><a href="https://w3c.github.io/wcag/guidelines/">Web Content Accessibility Guidelines (WCAG)</a></cite>, A. Kirkpatrick, J. O Connor, A. Campbell, M. Cooper. W3C.</dd>
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