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onion/js/utils/inject_utils.js
2015-12-08 20:55:13 +01:00

68 lines
1.5 KiB
JavaScript

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