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// Handle errors around fetching, parsing and registering import maps.
window.onScriptError = event => {
window.registrationResult = {type: 'FetchError', error: event.error};
return false;
};
window.windowErrorHandler = event => {
window.registrationResult = {type: 'ParseError', error: event.error};
return false;
};
window.addEventListener('error', window.windowErrorHandler);
// Handle specifier resolution requests from the parent frame.
// For failures, we post error names and messages instead of error
// objects themselves and re-create error objects later, to avoid
// issues around serializing error objects which is a quite new feature.
window.addEventListener('message', event => {
if (event.data.action !== 'resolve') {
parent.postMessage({
type: 'Failure',
result: 'Error',
message: 'Invalid Action: ' + event.data.action}, '*');
return;
}
// To respond to a resolution request, we:
// 1. Save the specifier to resolve into a global.
// 2. Update the document's base URL to the requested base URL.
// 3. Create a new inline script, parsed with that base URL, which
// resolves the saved specifier using import.meta.resolve(), and
// sents the result to the parent window.
window.specifierToResolve = event.data.specifier;
document.querySelector('base').href = event.data.baseURL;
const inlineScript = document.createElement('script');
inlineScript.type = 'module';
inlineScript.textContent = `
try {
const result = import.meta.resolve(window.specifierToResolve);
parent.postMessage({type: 'ResolutionSuccess', result}, '*');
} catch (e) {
parent.postMessage(
{type: 'Failure', result: e.name, message: e.message}, '*');
}
`;
document.body.append(inlineScript);
});