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73 lines
1.6 KiB
JavaScript
73 lines
1.6 KiB
JavaScript
'use strict';
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import Q from 'q';
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let mapAttr = {
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link: 'href',
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script: 'src'
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};
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let mapTag = {
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js: 'script',
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css: 'link'
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};
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function injectTag(tag, src) {
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return Q.Promise((resolve, reject) => {
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if (isPresent(tag, src)) {
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resolve();
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} else {
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let attr = mapAttr[tag];
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let element = document.createElement(tag);
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if (tag === 'script') {
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element.onload = () => resolve();
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element.onerror = () => reject();
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} else {
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resolve();
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}
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document.head.appendChild(element);
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element[attr] = src;
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if (tag === 'link') {
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element.rel = 'stylesheet';
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}
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}
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});
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}
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function isPresent(tag, src) {
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let attr = mapAttr[tag];
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let query = `head > ${tag}[${attr}="${src}"]`;
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return document.querySelector(query);
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}
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function injectStylesheet(src) {
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return injectTag('link', src);
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}
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function injectScript(src) {
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return injectTag('source', src);
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}
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function inject(src) {
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let ext = src.split('.').pop();
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let tag = mapTag[ext];
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if (!tag) {
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throw new Error(`Cannot inject ${src} in the DOM, cannot guess the tag name from extension "${ext}". Valid extensions are "js" and "css".`);
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}
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return injectTag(tag, src);
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}
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export const InjectInHeadUtils = {
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/**
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* Provide functions to inject `<script>` and `<link>` in `<head>`.
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* Useful when you have to load a huge external library and
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* you don't want to embed everything inside the build file.
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*/
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isPresent,
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injectStylesheet,
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injectScript,
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inject
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};
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