custom-element-exception.html

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This WPT test may be referenced by the following Test IDs:
- /html/semantics/scripting-1/the-script-element/module/custom-element-exception.html - WPT Dashboard Interop Dashboard

<!DOCTYPE html>

<title>Handling of exceptions in custom element constructors</title>

<script src="/resources/testharness.js"></script>

<script src="/resources/testharnessreport.js"></script>

<script>

    setup({allow_uncaught_exception: true});

    window.log = [];

    window.addEventListener("error", ev => log.push(ev.error));

    const test_load = async_test(

        "Test that exceptions from the constructor of a custom element " +

        "inside a module are propagated as expected.\n");

    window.addEventListener("load", test_load.step_func_done(ev => {

      assert_equals(1, log.length);

      const exception = log[0];

      assert_true(exception instanceof Error);

      assert_equals(exception.message, "custom element error");

    }));

</script>

<script type="module">

    class XThrower extends HTMLElement {

      constructor() {

        super();

        throw new Error("custom element error");

    customElements.define("x-thrower", XThrower);

    document.createElement("x-thrower");

</script>