lib/preview-web/src/simulate-pageload.ts
import global from 'global';
const { document } = global;
// https://html.spec.whatwg.org/multipage/scripting.html
const runScriptTypes = [
'application/javascript',
'application/ecmascript',
'application/x-ecmascript',
'application/x-javascript',
'text/ecmascript',
'text/javascript',
'text/javascript1.0',
'text/javascript1.1',
'text/javascript1.2',
'text/javascript1.3',
'text/javascript1.4',
'text/javascript1.5',
'text/jscript',
'text/livescript',
'text/x-ecmascript',
'text/x-javascript',
// Support modern javascript
'module',
];
const SCRIPT = 'script';
const SCRIPTS_ROOT_ID = 'scripts-root';
// trigger DOMContentLoaded
export function simulateDOMContentLoaded() {
const DOMContentLoadedEvent = document.createEvent('Event');
DOMContentLoadedEvent.initEvent('DOMContentLoaded', true, true);
document.dispatchEvent(DOMContentLoadedEvent);
}
function insertScript($script: any, callback: any, $scriptRoot: any) {
const scriptEl = document.createElement('script');
scriptEl.type = $script.type === 'module' ? 'module' : 'text/javascript';
if ($script.src) {
scriptEl.onload = callback;
scriptEl.onerror = callback;
scriptEl.src = $script.src;
} else {
scriptEl.textContent = $script.innerText;
}
// re-insert the script tag so it executes.
if ($scriptRoot) $scriptRoot.appendChild(scriptEl);
else document.head.appendChild(scriptEl);
// clean-up
$script.parentNode.removeChild($script);
// run the callback immediately for inline scripts
if (!$script.src) callback();
}
// runs an array of async functions in sequential order
/* eslint-disable no-param-reassign, no-plusplus */
function insertScriptsSequentially(scriptsToExecute: any[], callback: any, index = 0) {
scriptsToExecute[index](() => {
index++;
if (index === scriptsToExecute.length) {
callback();
} else {
insertScriptsSequentially(scriptsToExecute, callback, index);
}
});
}
export function simulatePageLoad($container: any) {
let $scriptsRoot = document.getElementById(SCRIPTS_ROOT_ID);
if (!$scriptsRoot) {
$scriptsRoot = document.createElement('div');
$scriptsRoot.id = SCRIPTS_ROOT_ID;
document.body.appendChild($scriptsRoot);
} else {
$scriptsRoot.innerHTML = '';
}
const $scripts = Array.from($container.querySelectorAll(SCRIPT));
if ($scripts.length) {
const scriptsToExecute: any[] = [];
$scripts.forEach(($script: any) => {
const typeAttr = $script.getAttribute('type');
// only run script tags without the type attribute
// or with a javascript mime attribute value from the list
if (!typeAttr || runScriptTypes.includes(typeAttr)) {
scriptsToExecute.push((callback: any) => insertScript($script, callback, $scriptsRoot));
}
});
// insert the script tags sequentially
// to preserve execution order
if (scriptsToExecute.length) {
insertScriptsSequentially(scriptsToExecute, simulateDOMContentLoaded, undefined);
}
} else {
simulateDOMContentLoaded();
}
}