Add Clay/htmlEncode extension (#1126)

Co-authored-by: ClaytonTDM <[email protected]>

extensions/Clay/htmlEncode.js

@@ -0,0 +1,54 @@
+// Name: HTML Encode
+// ID: clayhtmlencode
+// Description: Escape untrusted text to safely include in HTML.
+// By: ClaytonTDM
+
+(function (Scratch) {
+  "use strict";
+
+  class HtmlEncode {
+    getInfo() {
+      return {
+        id: "claytonhtmlencode",
+        name: "HTML Encode",
+        blocks: [
+          {
+            opcode: "encode",
+            blockType: Scratch.BlockType.REPORTER,
+            text: "encode [text] as HTML-safe",
+            arguments: {
+              text: {
+                type: Scratch.ArgumentType.STRING,
+                // don't use a script tag as the example here as the closing script
+                // tag might break things when this extension gets inlined in packed
+                // projects
+                defaultValue: "<h1>Hello!</h1>",
+              },
+            },
+          },
+        ],
+      };
+    }
+
+    encode({ text }) {
+      return Scratch.Cast.toString(text).replace(/["'&<>]/g, (a) => {
+        switch (a) {
+          case "&":
+            return "&amp;";
+          case '"':
+            return "&apos;";
+          case "'":
+            return "&quot;";
+          case ">":
+            return "&gt;";
+          case "<":
+            return "&lt;";
+        }
+        // this should never happen...
+        return "";
+      });
+    }
+  }
+
+  Scratch.extensions.register(new HtmlEncode());
+})(Scratch);

extensions/extensions.json

@@ -17,6 +17,7 @@
   "sound",
   "Lily/Video",
   "iframe",
+  "Clay/htmlEncode",
   "Xeltalliv/clippingblending",
   "clipboard",
   "obviousAlexC/penPlus",