webpack/lib/asset/AssetResourcePrefetchRuntim...

83 lines
2.0 KiB
JavaScript

/*
MIT License http://www.opensource.org/licenses/mit-license.php
Author Tobias Koppers @sokra
*/
"use strict";
const RuntimeGlobals = require("../RuntimeGlobals");
const RuntimeModule = require("../RuntimeModule");
const Template = require("../Template");
/** @typedef {import("../Compilation")} Compilation */
class AssetResourcePrefetchRuntimeModule extends RuntimeModule {
/**
* @param {string} type "prefetch" or "preload"
*/
constructor(type) {
super(`asset ${type}`, RuntimeModule.STAGE_ATTACH);
this._type = type;
}
/**
* @returns {string | null} runtime code
*/
generate() {
const { compilation } = this;
if (!compilation) return null;
const { runtimeTemplate, outputOptions } = compilation;
const fnName =
this._type === "prefetch"
? RuntimeGlobals.prefetchAsset
: RuntimeGlobals.preloadAsset;
const crossOriginLoading = outputOptions.crossOriginLoading;
return Template.asString([
`${fnName} = ${runtimeTemplate.basicFunction(
"moduleId, as, fetchPriority, relative",
[
"var url;",
"if (relative) {",
Template.indent([
`url = new ${RuntimeGlobals.relativeUrl}(${RuntimeGlobals.require}(moduleId));`
]),
"} else {",
Template.indent([
`url = new URL(${RuntimeGlobals.require}(moduleId), ${RuntimeGlobals.baseURI});`
]),
"}",
"",
"var link = document.createElement('link');",
`link.rel = '${this._type}';`,
"if (as) link.as = as;",
"link.href = url.href;",
"",
"if (fetchPriority) {",
Template.indent([
"link.fetchPriority = fetchPriority;",
"link.setAttribute('fetchpriority', fetchPriority);"
]),
"}",
"",
crossOriginLoading
? Template.asString([
"if (link.href.indexOf(window.location.origin + '/') !== 0) {",
Template.indent([
`link.crossOrigin = ${JSON.stringify(crossOriginLoading)};`
]),
"}"
])
: "",
"",
"document.head.appendChild(link);"
]
)};`
]);
}
}
module.exports = AssetResourcePrefetchRuntimeModule;