Add new operation: Template

package.json

@@ -132,6 +132,7 @@
     "file-saver": "^2.0.5",
     "flat": "^6.0.1",
     "geodesy": "1.1.3",
+    "handlebars": "^4.7.8",
     "highlight.js": "^11.9.0",
     "ieee754": "^1.2.1",
     "jimp": "^0.22.12",

src/core/config/Categories.json

@@ -373,7 +373,8 @@
             "Extract EXIF",
             "Extract ID3",
             "Extract Files",
-            "RAKE"
+            "RAKE",
+            "Template"
         ]
     },
     {

src/core/operations/Template.mjs

@@ -0,0 +1,53 @@
+/**
+ * @author kendallgoto [k@kgo.to]
+ * @copyright Crown Copyright 2025
+ * @license Apache-2.0
+ */
+
+import Operation from "../Operation.mjs";
+import OperationError from "../errors/OperationError.mjs";
+import Handlebars from "handlebars";
+
+/**
+ * Template operation
+ */
+class Template extends Operation {
+
+    /**
+     * Template constructor
+     */
+    constructor() {
+        super();
+
+        this.name = "Template";
+        this.module = "Handlebars";
+        this.description = "Render a template with Handlebars/Mustache substituting variables using JSON input. Templates will be rendered to plain-text only, to prevent XSS.";
+        this.infoURL = "https://handlebarsjs.com/";
+        this.inputType = "JSON";
+        this.outputType = "string";
+        this.args = [
+            {
+                name: "Template definition (.handlebars)",
+                type: "text",
+                value: ""
+            }
+        ];
+    }
+
+    /**
+     * @param {JSON} input
+     * @param {Object[]} args
+     * @returns {string}
+     */
+    run(input, args) {
+        const [templateStr] = args;
+        try {
+            const template = Handlebars.compile(templateStr);
+            return template(input);
+        } catch (e) {
+            throw new OperationError(e);
+        }
+    }
+}
+
+export default Template;

tests/operations/index.mjs

@@ -157,6 +157,7 @@ import "./tests/Subsection.mjs";
 import "./tests/SwapCase.mjs";
 import "./tests/SymmetricDifference.mjs";
 import "./tests/TakeNthBytes.mjs";
+import "./tests/Template.mjs";
 import "./tests/TextEncodingBruteForce.mjs";
 import "./tests/ToFromInsensitiveRegex.mjs";
 import "./tests/TranslateDateTimeFormat.mjs";

tests/operations/tests/Template.mjs

@@ -0,0 +1,53 @@
+/**
+ * @author kendallgoto [k@kgo.to]
+ * @copyright Crown Copyright 2025
+ * @license Apache-2.0
+ */
+
+import TestRegister from "../../lib/TestRegister.mjs";
+TestRegister.addTests([
+    {
+        "name": "Template: Simple Print",
+        "input": "{}",
+        "expectedOutput": "Hello, world!",
+        "recipeConfig": [
+            {
+                "op": "Template",
+                "args": ["Hello, world!"]
+            }
+        ]
+    },
+    {
+        "name": "Template: Print Basic Variables",
+        "input": "{\"one\": 1, \"two\": 2}",
+        "expectedOutput": "1 2",
+        "recipeConfig": [
+            {
+                "op": "Template",
+                "args": ["{{ one }} {{ two }}"]
+            }
+        ]
+    },
+    {
+        "name": "Template: Partials",
+        "input": "{\"users\":[{\"name\":\"Someone\",\"age\":25},{\"name\":\"Someone Else\",\"age\":32}]}",
+        "expectedOutput": "Name: Someone\nAge: 25\n\nName: Someone Else\nAge: 32\n\n",
+        "recipeConfig": [
+            {
+                "op": "Template",
+                "args": ["{{#*inline \"user\"}}\nName: {{ name }}\nAge: {{ age }}\n{{/inline}}\n{{#each users}}\n{{> user}}\n\n{{/each}}"]
+            }
+        ]
+    },
+    {
+        "name": "Template: Disallow XSS",
+        "input": "{\"test\": \"<script></script>\"}",
+        "expectedOutput": "<script></script>&lt;script&gt;&lt;/script&gt;",
+        "recipeConfig": [
+            {
+                "op": "Template",
+                "args": ["<script></script>{{ test }}"]
+            }
+        ]
+    }
+]);