Add mustache plugin.

.editorconfig

@@ -13,5 +13,8 @@ insert_final_newline = false
 [*.ejs]
 insert_final_newline = false
 
+[*.mustache]
+insert_final_newline = false
+
 [*.yml]
 indent_style = space

handlebars/handlebarsConfig.js

@@ -1,18 +1,18 @@
 const fs = require("node:fs");
+
 const handlebars = require("handlebars");
 const fastglob = require("fast-glob");
 const { TemplatePath } = require("@11ty/eleventy-utils");
 const debug = require("debug")("Eleventy:Handlebars");
 
-async function getPartials(directories) {
+async function getPartials(directories, extensions) {
 	if (!directories?.includes) {
 		return {
 			files: [],
 			partials: {},
 		};
 	}
 
-	let extensions = ["hbs"];
 	let results = [];
 	let partialFiles = [];
 	let prefix = directories.includes + "**/*.";
@@ -114,7 +114,7 @@ module.exports = function (eleventyConfig, options = {}) {
 	let files = [];
 	eleventyConfig.on("eleventy.resourceModified", async modifiedPath => {
 		if(files.includes(modifiedPath)) {
-			ret = await getPartials(eleventyConfig.directories);
+			ret = await getPartials(eleventyConfig.directories, ["hbs"]);
 			files = ret.files;
 			library.registerPartial(ret.partials);
 		}
@@ -123,7 +123,7 @@ module.exports = function (eleventyConfig, options = {}) {
 	eleventyConfig.addExtension("hbs", {
 		init: async () => {
 			// Cache the partials
-			let ret = await getPartials(eleventyConfig.directories);
+			let ret = await getPartials(eleventyConfig.directories, ["hbs"]);
 			files = ret.files;
 			library.registerPartial(ret.partials);
 		},

mustache/README.md

@@ -0,0 +1,36 @@
+# `@11ty/eleventy-plugin-mustache`
+
+Adds support for `.mustache` (Embedded JavaScript templates) files in Eleventy v3.0 and newer. Support for [`mustache` was moved out of core as part of Project Slipstream](https://github.com/11ty/eleventy/pull/3074).
+
+- 11ty Docs https://www.11ty.dev/docs/languages/mustache/
+- `mustache` package: https://github.com/janl/mustache.js
+
+## Installation
+
+```sh
+npm install @11ty/eleventy-plugin-mustache
+```
+
+Add to your configuration file (ESM version shown):
+
+```js
+import mustachePlugin from "@11ty/eleventy-plugin-mustache";
+
+export default function (eleventyConfig) {
+	eleventyConfig.addPlugin(mustachePlugin);
+}
+```
+
+Use more options:
+
+```js
+import mustache from "mustache";
+import mustachePlugin from "@11ty/eleventy-plugin-mustache";
+
+export default function (eleventyConfig) {
+	eleventyConfig.addPlugin(mustachePlugin, {
+		// Override the `mustache` library instance
+		eleventyLibraryOverride: mustache,
+	});
+}
+```

mustache/mustacheConfig.js

@@ -0,0 +1,108 @@
+const fs = require("node:fs");
+
+const mustache = require("mustache");
+const fastglob = require("fast-glob");
+const { TemplatePath } = require("@11ty/eleventy-utils");
+const debug = require("debug")("Eleventy:Mustache");
+
+async function getPartials(directories, extensions) {
+	if (!directories?.includes) {
+		return {
+			files: [],
+			partials: {},
+		};
+	}
+
+	let results = [];
+	let partialFiles = [];
+	let prefix = directories.includes + "**/*.";
+
+	await Promise.all(
+		extensions.map(async function (extension) {
+			partialFiles = partialFiles.concat(
+				await fastglob(prefix + extension, {
+					caseSensitiveMatch: false,
+					dot: true,
+				})
+			);
+		})
+	);
+
+	results = await Promise.all(
+		partialFiles.map((partialFile) => {
+			partialFile = TemplatePath.addLeadingDotSlash(partialFile);
+			let partialPath = TemplatePath.stripLeadingSubPath(partialFile, directories.includes);
+			let partialPathNoExt = partialPath;
+			extensions.forEach(function (extension) {
+				partialPathNoExt = TemplatePath.removeExtension(partialPathNoExt, "." + extension);
+			});
+
+			return fs.promises
+				.readFile(partialFile, {
+					encoding: "utf8",
+				})
+				.then((content) => {
+					return {
+						content,
+						path: partialPathNoExt,
+					};
+				});
+		})
+	);
+
+	let partials = {};
+	for (let result of results) {
+		partials[result.path] = result.content;
+	}
+
+	debug(
+		`${directories.includes}/*.{${extensions}} found partials for: %o`,
+		Object.keys(partials)
+	);
+
+	return {
+		files: partialFiles,
+		partials,
+	};
+}
+
+module.exports = function (eleventyConfig, options = {}) {
+	options = Object.assign(
+		{
+			// Override the ejs instance
+			eleventyLibraryOverride: undefined,
+		},
+		options || {},
+	);
+
+	// Remove eleventy specific things from `options`
+	let libraryOverride = options.eleventyLibraryOverride;
+	delete options.eleventyLibraryOverride;
+
+	eleventyConfig.addTemplateFormats("mustache");
+
+	// Partials
+	let files = [];
+	let partials = {};
+	eleventyConfig.on("eleventy.resourceModified", async modifiedPath => {
+		if(files.includes(modifiedPath)) {
+			ret = await getPartials(eleventyConfig.directories, ["mustache"]);
+			files = ret.files;
+			partials = ret.partials;
+		}
+	});
+
+	eleventyConfig.addExtension("mustache", {
+		init: async () => {
+			// Cache the partials
+			let ret = await getPartials(eleventyConfig.directories, ["mustache"]);
+			files = ret.files;
+			partials = ret.partials;
+		},
+		compile: (str, inputPath) => {
+			return function(data) {
+				return (libraryOverride || mustache).render(str, data, partials);
+			};
+		},
+	});
+};

mustache/package.json

@@ -0,0 +1,33 @@
+{
+	"name": "@11ty/eleventy-plugin-mustache",
+	"version": "1.0.0-alpha.1",
+	"description": "The `mustache` template language plugin for Eleventy v3 and newer.",
+	"main": "mustacheConfig.js",
+	"type": "commonjs",
+	"engines": {
+		"node": ">=18"
+	},
+	"publishConfig": {
+		"access": "public"
+	},
+	"files": [
+		"!test"
+	],
+	"funding": {
+		"type": "opencollective",
+		"url": "https://opencollective.com/11ty"
+	},
+	"author": "Zach Leatherman <[email protected]> (https://zachleat.com/)",
+	"repository": {
+		"type": "git",
+		"url": "git://github.com/11ty/eleventy.git"
+	},
+	"bugs": "https://github.com/11ty/eleventy/issues",
+	"homepage": "https://www.11ty.dev/",
+	"scripts": {
+		"test": "echo \"Error: run tests from root directory\" && exit 1"
+	},
+	"dependencies": {
+		"mustache": "^4.2.0"
+	}
+}

mustache/test/mustache-test.mjs

@@ -0,0 +1,96 @@
+import { strictEqual } from "node:assert";
+import { test, describe } from "node:test";
+import path from "node:path";
+import { fileURLToPath } from "node:url";
+
+import mustache from "mustache";
+import Eleventy from "@11ty/eleventy";
+
+import MustachePlugin from "../mustacheConfig.js";
+
+const dirname = path.dirname(import.meta.url);
+const input = fileURLToPath(path.join(dirname, "stubs"));
+
+async function getTestResults(configCallback, options = {}) {
+	let elev = new Eleventy(input, undefined, {
+		config: (eleventyConfig) => {
+			eleventyConfig.addPlugin(MustachePlugin, options);
+
+			configCallback(eleventyConfig);
+		},
+	});
+
+	return await elev.toJSON();
+}
+
+test("Mustache standard template", async function () {
+	let [result] = await getTestResults((eleventyConfig) => {
+		eleventyConfig.addTemplate("sample.mustache", "<p>{{name}}</p>", {
+			name: "Zach",
+		});
+	});
+
+	strictEqual(result.content, `<p>Zach</p>`);
+});
+
+describe("Partials", () => {
+	test("Partial raw text", async function () {
+		let [result] = await getTestResults((eleventyConfig) => {
+			eleventyConfig.addTemplate("sample.mustache", "<p>{{> include}}</p>");
+		});
+
+		strictEqual(result.content, `<p>This is an include.</p>`);
+	});
+
+	test("Partial variable in content", async function () {
+		let [result] = await getTestResults((eleventyConfig) => {
+			eleventyConfig.addTemplate("sample.mustache", "<p>{{> includevar}}</p>", { name: "Zach" });
+		});
+
+		strictEqual(result.content, `<p>This is a Zach.</p>`);
+	});
+
+	test("Partial in subdir", async function () {
+		let [result] = await getTestResults((eleventyConfig) => {
+			eleventyConfig.addTemplate("sample.mustache", "<p>{{> dir/include-dir}}</p>", { name: "Zach" });
+		});
+
+		strictEqual(result.content, `<p>Include in dir.</p>`);
+	});
+});
+
+test("Library override", async function () {
+	let [result] = await getTestResults((eleventyConfig) => {
+		eleventyConfig.addTemplate("sample.mustache", "<p>{{name}}</p>", { name: "Zach" });
+	}, {
+		eleventyLibraryOverride: mustache,
+	});
+
+	strictEqual(result.content, `<p>Zach</p>`);
+});
+
+describe("Escaped/unescaped output", () => {
+	test("Escaped output (no HTML)", async function () {
+		let [result] = await getTestResults((eleventyConfig) => {
+			eleventyConfig.addTemplate("sample.mustache", "<p>{{{name}}}</p>", { name: "Zach" });
+		});
+
+		strictEqual(result.content, `<p>Zach</p>`);
+	});
+
+	test("Escaped output (HTML)", async function () {
+		let [result] = await getTestResults((eleventyConfig) => {
+			eleventyConfig.addTemplate("sample.mustache", "<p>{{name}}</p>", { name: "<b>Zach</b>" });
+		});
+
+		strictEqual(result.content, `<p>&lt;b&gt;Zach&lt;&#x2F;b&gt;</p>`);
+	});
+
+	test("Unescaped output (HTML)", async function () {
+		let [result] = await getTestResults((eleventyConfig) => {
+			eleventyConfig.addTemplate("sample.mustache", "<p>{{{name}}}</p>", { name: "<b>Zach</b>" });
+		});
+
+		strictEqual(result.content, `<p><b>Zach</b></p>`);
+	});
+})

mustache/test/stubs/_includes/dir/include-dir.mustache

@@ -0,0 +1 @@
+Include in dir.

mustache/test/stubs/_includes/include.mustache

@@ -0,0 +1 @@
+This is an include.

mustache/test/stubs/_includes/includevar.mustache

@@ -0,0 +1 @@
+This is a {{name}}.