disallow document.write and document.writeln (fixes #2)

lib/rules/no-unsafe-innerhtml.js

@@ -101,7 +101,15 @@ module.exports = function (context) {
             if ("property" in node.callee) {
                 if (node.callee.property.name === "insertAdjacentHTML") {
                     if (!allowedExpression(node.arguments[1], node.parent)) {
-                        context.report(node, "Unsafe call to insertAdjacentHTML"); // report error
+                        context.report(node, "Unsafe call to insertAdjacentHTML");
+                    }
+                } else if (context.getSource(node.callee) === "document.write") {
+                    if (!allowedExpression(node.arguments[0], node.parent)) {
+                        context.report(node, "Unsafe call to document.write");
+                    }
+                } else if (context.getSource(node.callee) === "document.writeln") {
+                    if (!allowedExpression(node.arguments[0], node.parent)) {
+                        context.report(node, "Unsafe call to" + " document.writeln");
                     }
                 }
             }

tests/rules/no-unsafe-innerhtml.js

@@ -103,7 +103,17 @@ eslintTester.run("no-unsafe-innerhtml", rule, {
         {
             code: "y.innerHTML = '<span>' + 5 + '</span>';",
             ecmaFeatures: { templateStrings: true }
+        },
+        // document.write/writeln
+        {
+            code: "document.write('lulz');",
+            ecmaFeatures: { templateStrings: true }
+        },
+        {
+            code: "document.writeln(Sanitizer.escapeHTML`<em>${evil}</em>`);",
+            ecmaFeatures: { templateStrings: true }
         }
+
     ],
 
     // Examples of code that should trigger the rule
@@ -186,6 +196,25 @@ eslintTester.run("no-unsafe-innerhtml", rule, {
                     type: "AssignmentExpression"
                 }
             ]
+        },
+        // document.write / writeln
+        {
+            code: "document.write('<span>'+ htmlInput + '</span>');",
+            errors: [
+                {
+                    message: "Unsafe call to document.write",
+                    type: "CallExpression"
+                }
+            ]
+        },
+        {
+            code: "document.writeln(evil);",
+            errors: [
+                {
+                    message: "Unsafe call to document.writeln",
+                    type: "CallExpression"
+                }
+            ]
         }
     ]
 });