1 files changed, 77 insertions, 0 deletions
diff --git a/tools/node_modules/eslint/lib/rules/valid-typeof.js b/tools/node_modules/eslint/lib/rules/valid-typeof.js
new file mode 100644
index 0000000000..fba4cc5712
--- /dev/null
+++ b/tools/node_modules/eslint/lib/rules/valid-typeof.js
@@ -0,0 +1,77 @@
+/**
+ * @fileoverview Ensures that the results of typeof are compared against a valid string
+ * @author Ian Christian Myers
+ */
+"use strict";
+
+//------------------------------------------------------------------------------
+// Rule Definition
+//------------------------------------------------------------------------------
+
+module.exports = {
+    meta: {
+        docs: {
+            description: "enforce comparing `typeof` expressions against valid strings",
+            category: "Possible Errors",
+            recommended: true
+        },
+
+        schema: [
+            {
+                type: "object",
+                properties: {
+                    requireStringLiterals: {
+                        type: "boolean"
+                    }
+                },
+                additionalProperties: false
+            }
+        ]
+    },
+
+    create(context) {
+
+        const VALID_TYPES = ["symbol", "undefined", "object", "boolean", "number", "string", "function"],
+            OPERATORS = ["==", "===", "!=", "!=="];
+
+        const requireStringLiterals = context.options[0] && context.options[0].requireStringLiterals;
+
+        /**
+         * Determines whether a node is a typeof expression.
+         * @param {ASTNode} node The node
+         * @returns {boolean} `true` if the node is a typeof expression
+         */
+        function isTypeofExpression(node) {
+            return node.type === "UnaryExpression" && node.operator === "typeof";
+        }
+
+        //--------------------------------------------------------------------------
+        // Public
+        //--------------------------------------------------------------------------
+
+        return {
+
+            UnaryExpression(node) {
+                if (isTypeofExpression(node)) {
+                    const parent = context.getAncestors().pop();
+
+                    if (parent.type === "BinaryExpression" && OPERATORS.indexOf(parent.operator) !== -1) {
+                        const sibling = parent.left === node ? parent.right : parent.left;
+
+                        if (sibling.type === "Literal" || sibling.type === "TemplateLiteral" && !sibling.expressions.length) {
+                            const value = sibling.type === "Literal" ? sibling.value : sibling.quasis[0].value.cooked;
+
+                            if (VALID_TYPES.indexOf(value) === -1) {
+                                context.report({ node: sibling, message: "Invalid typeof comparison value." });
+                            }
+                        } else if (requireStringLiterals && !isTypeofExpression(sibling)) {
+                            context.report({ node: sibling, message: "Typeof comparisons should be to string literals." });
+                        }
+                    }
+                }
+            }
+
+        };
+
+    }
+};