feat: add to fullwidth operation

src/core/config/Categories.json

@@ -49,6 +49,7 @@
             "Escape Unicode Characters",
             "Unescape Unicode Characters",
             "Normalise Unicode",
+            "To Fullwidth",
             "To Quoted Printable",
             "From Quoted Printable",
             "To Punycode",
@@ -591,4 +592,4 @@
             "Comment"
         ]
     }
-]
+]

src/core/operations/ToFullwidth.mjs

@@ -0,0 +1,57 @@
+/**
+ * @author jyeu [chen@jyeu.xyz]
+ * @copyright Crown Copyright 2026
+ * @license Apache-2.0
+ */
+
+import Operation from "../Operation.mjs";
+
+/**
+ * To Fullwidth operation
+ */
+class ToFullwidth extends Operation {
+    /**
+     * ToFullwidth constructor
+     */
+    constructor() {
+        super();
+
+        this.name = "To Fullwidth";
+        this.module = "Encodings";
+        this.description =
+            "Converts ASCII (halfwidth) characters to their fullwidth Unicode equivalents (U+FF01–U+FF5E). Commonly used in security testing to bypass WAF keyword filters, evade regex-based blocklists, and exploit Unicode normalization (NFKC/NFKD) vulnerabilities in web applications and path parsers. For example, <code>/ａdmin</code> may bypass a WAF rule matching <code>/admin</code> if the backend normalises Unicode before routing.";
+        this.infoURL =
+            "https://wikipedia.org/wiki/Halfwidth_and_fullwidth_forms_(Unicode_block)";
+        this.inputType = "string";
+        this.outputType = "string";
+        this.args = [];
+    }
+
+    /**
+     * @param {string} input
+     * @param {never} _args
+     * @returns {string}
+     */
+    run(input, _args) {
+        let output = "";
+
+        for (const char of input) {
+            const code = char.codePointAt(0);
+
+            if (code === 0x20) {
+                // Regular space -> Ideographic space (U+3000)
+                output += "\u3000";
+            } else if (code >= 0x21 && code <= 0x7e) {
+                // Visible ASCII characters -> Fullwidth equivalents (U+FF01–U+FF5E)
+                output += String.fromCodePoint(code + 0xfee0);
+            } else {
+                // Non-ASCII characters (CJK, newlines, etc.) are passed through unchanged
+                output += char;
+            }
+        }
+
+        return output;
+    }
+}
+
+export default ToFullwidth;

tests/operations/index.mjs

@@ -167,6 +167,7 @@ import "./tests/TakeNthBytes.mjs";
 import "./tests/Template.mjs";
 import "./tests/TextEncodingBruteForce.mjs";
 import "./tests/TextIntegerConverter.mjs";
+import "./tests/ToFullwidth.mjs";
 import "./tests/ToFromInsensitiveRegex.mjs";
 import "./tests/TranslateDateTimeFormat.mjs";
 import "./tests/Typex.mjs";

tests/operations/tests/ToFullwidth.mjs

@@ -0,0 +1,144 @@
+/**
+ * To Fullwidth tests.
+ *
+ * @author jyeu [chen@jyeu.xyz]
+ *
+ * @copyright Crown Copyright 2026
+ * @license Apache-2.0
+ */
+import TestRegister from "../../lib/TestRegister.mjs";
+
+TestRegister.addTests([
+    {
+        name: "To Fullwidth: empty string",
+        input: "",
+        expectedOutput: "",
+        recipeConfig: [
+            {
+                op: "To Fullwidth",
+                args: [],
+            },
+        ],
+    },
+    {
+        name: "To Fullwidth: lowercase letters",
+        input: "admin",
+        expectedOutput: "\uFF41\uFF44\uFF4D\uFF49\uFF4E",
+        recipeConfig: [
+            {
+                op: "To Fullwidth",
+                args: [],
+            },
+        ],
+    },
+    {
+        name: "To Fullwidth: uppercase letters",
+        input: "ADMIN",
+        expectedOutput: "\uFF21\uFF24\uFF2D\uFF29\uFF2E",
+        recipeConfig: [
+            {
+                op: "To Fullwidth",
+                args: [],
+            },
+        ],
+    },
+    {
+        name: "To Fullwidth: digits",
+        input: "0123456789",
+        expectedOutput: "\uFF10\uFF11\uFF12\uFF13\uFF14\uFF15\uFF16\uFF17\uFF18\uFF19",
+        recipeConfig: [
+            {
+                op: "To Fullwidth",
+                args: [],
+            },
+        ],
+    },
+    {
+        name: "To Fullwidth: space becomes ideographic space (U+3000)",
+        input: "hello world",
+        expectedOutput: "\uFF48\uFF45\uFF4C\uFF4C\uFF4F\u3000\uFF57\uFF4F\uFF52\uFF4C\uFF44",
+        recipeConfig: [
+            {
+                op: "To Fullwidth",
+                args: [],
+            },
+        ],
+    },
+    {
+        name: "To Fullwidth: common punctuation and symbols",
+        input: "!@#$%^&*()_+-=[]{}|;':\",./<>?",
+        expectedOutput: "\uFF01\uFF20\uFF03\uFF04\uFF05\uFF3E\uFF06\uFF0A\uFF08\uFF09\uFF3F\uFF0B\uFF0D\uFF1D\uFF3B\uFF3D\uFF5B\uFF5D\uFF5C\uFF1B\uFF07\uFF1A\uFF02\uFF0C\uFF0E\uFF0F\uFF1C\uFF1E\uFF1F",
+        recipeConfig: [
+            {
+                op: "To Fullwidth",
+                args: [],
+            },
+        ],
+    },
+    {
+        name: "To Fullwidth: slash for WAF bypass simulation",
+        input: "/admin/secret",
+        expectedOutput: "\uFF0F\uFF41\uFF44\uFF4D\uFF49\uFF4E\uFF0F\uFF53\uFF45\uFF43\uFF52\uFF45\uFF54",
+        recipeConfig: [
+            {
+                op: "To Fullwidth",
+                args: [],
+            },
+        ],
+    },
+    {
+        name: "To Fullwidth: non-ASCII characters pass through unchanged",
+        input: "你好世界",
+        expectedOutput: "你好世界",
+        recipeConfig: [
+            {
+                op: "To Fullwidth",
+                args: [],
+            },
+        ],
+    },
+    {
+        name: "To Fullwidth: newline passes through unchanged",
+        input: "line1\nline2",
+        expectedOutput: "\uFF4C\uFF49\uFF4E\uFF45\uFF11\n\uFF4C\uFF49\uFF4E\uFF45\uFF12",
+        recipeConfig: [
+            {
+                op: "To Fullwidth",
+                args: [],
+            },
+        ],
+    },
+    {
+        name: "To Fullwidth: mixed ASCII and non-ASCII",
+        input: "hello,世界!",
+        expectedOutput: "\uFF48\uFF45\uFF4C\uFF4C\uFF4F\uFF0C世界\uFF01",
+        recipeConfig: [
+            {
+                op: "To Fullwidth",
+                args: [],
+            },
+        ],
+    },
+    {
+        name: "To Fullwidth: boundary character 0x21 (!)",
+        input: "!",
+        expectedOutput: "\uFF01",
+        recipeConfig: [
+            {
+                op: "To Fullwidth",
+                args: [],
+            },
+        ],
+    },
+    {
+        name: "To Fullwidth: boundary character 0x7E (~)",
+        input: "~",
+        expectedOutput: "\uFF5E",
+        recipeConfig: [
+            {
+                op: "To Fullwidth",
+                args: [],
+            },
+        ],
+    },
+]);