gitlab-org--gitlab-foss/app/assets/javascripts/helpers/startup_css_helper.js

36 lines
1.1 KiB
JavaScript

const CSS_LOADED_EVENT = 'CSSLoaded';
const STARTUP_LINK_LOADED_EVENT = 'CSSStartupLinkLoaded';
const getAllStartupLinks = (() => {
let links = null;
return () => {
if (!links) {
links = Array.from(document.querySelectorAll('link[data-startupcss]'));
}
return links;
};
})();
const isStartupLinkLoaded = ({ dataset }) => dataset.startupcss === 'loaded';
const allLinksLoaded = () => getAllStartupLinks().every(isStartupLinkLoaded);
const handleStartupEvents = () => {
if (allLinksLoaded()) {
document.dispatchEvent(new CustomEvent(CSS_LOADED_EVENT));
document.removeEventListener(STARTUP_LINK_LOADED_EVENT, handleStartupEvents);
}
};
/* For `waitForCSSLoaded` methods, see docs.gitlab.com/ee/development/fe_guide/performance.html#important-considerations */
export const waitForCSSLoaded = (action = () => {}) => {
if (allLinksLoaded()) {
return new Promise((resolve) => {
action();
resolve();
});
}
return new Promise((resolve) => {
document.addEventListener(CSS_LOADED_EVENT, resolve, { once: true });
document.addEventListener(STARTUP_LINK_LOADED_EVENT, handleStartupEvents);
}).then(action);
};