1 files changed, 116 insertions, 17 deletions

diff --git a/tools/eslint/lib/rules/no-alert.js b/tools/eslint/lib/rules/no-alert.js
index 1f14b533d71..7d041eaf748 100644
--- a/tools/eslint/lib/rules/no-alert.js
+++ b/tools/eslint/lib/rules/no-alert.js
@@ -1,6 +1,8 @@
 /**
  * @fileoverview Rule to flag use of alert, confirm, prompt
  * @author Nicholas C. Zakas
+ * @copyright 2015 Mathias Schreck
+ * @copyright 2013 Nicholas C. Zakas
  */
 "use strict";
 
@@ -8,47 +10,144 @@
 // Helpers
 //------------------------------------------------------------------------------
 
-function matchProhibited(name) {
-    return name.match(/^(alert|confirm|prompt)$/);
+/**
+ * Checks if the given name is a prohibited identifier.
+ * @param {string} name The name to check
+ * @returns {boolean} Whether or not the name is prohibited.
+ */
+function isProhibitedIdentifier(name) {
+    return /^(alert|confirm|prompt)$/.test(name);
 }
 
-function report(context, node, result) {
-    context.report(node, "Unexpected {{name}}.", { name: result[1] });
+/**
+ * Reports the given node and identifier name.
+ * @param {RuleContext} context The ESLint rule context.
+ * @param {ASTNode} node The node to report on.
+ * @param {string} identifierName The name of the identifier.
+ * @returns {void}
+ */
+function report(context, node, identifierName) {
+    context.report(node, "Unexpected {{name}}.", { name: identifierName });
 }
 
+/**
+ * Returns the property name of a MemberExpression.
+ * @param {ASTNode} memberExpressionNode The MemberExpression node.
+ * @returns {string|undefined} Returns the property name if available, undefined else.
+ */
+function getPropertyName(memberExpressionNode) {
+    if (memberExpressionNode.computed) {
+        if (memberExpressionNode.property.type === "Literal") {
+            return memberExpressionNode.property.value;
+        }
+    } else {
+        return memberExpressionNode.property.name;
+    }
+}
+
+/**
+ * Finds the escope reference in the given scope.
+ * @param {Object} scope The scope to search.
+ * @param {ASTNode} node The identifier node.
+ * @returns {Reference|undefined} Returns the found reference or undefined if none were found.
+ */
+function findReference(scope, node) {
+    var references = scope.references.filter(function (reference) {
+        return reference.identifier.range[0] === node.range[0] &&
+            reference.identifier.range[1] === node.range[1];
+    });
+
+    if (references.length === 1) {
+        return references[0];
+    }
+}
+
+/**
+ * Checks if the given identifier name is shadowed in the given global scope.
+ * @param {Object} globalScope The global scope.
+ * @param {string} identifierName The identifier name to check
+ * @returns {boolean} Whether or not the name is shadowed globally.
+ */
+function isGloballyShadowed(globalScope, identifierName) {
+    return globalScope.variables.some(function (variable) {
+        return variable.name === identifierName && variable.defs.length > 0;
+    });
+}
+
+/**
+ * Checks if the given identifier node is shadowed in the given scope.
+ * @param {Object} scope The current scope.
+ * @param {Object} globalScope The global scope.
+ * @param {string} node The identifier node to check
+ * @returns {boolean} Whether or not the name is shadowed.
+ */
+function isShadowed(scope, globalScope, node) {
+    var reference = findReference(scope, node),
+        identifierName = node.name;
+
+    if (reference) {
+        if (reference.resolved || isGloballyShadowed(globalScope, identifierName)) {
+            return true;
+        }
+    }
+
+    return false;
+}
+
+/**
+ * Checks if the given identifier node is a ThisExpression in the global scope or the global window property.
+ * @param {Object} scope The current scope.
+ * @param {Object} globalScope The global scope.
+ * @param {string} node The identifier node to check
+ * @returns {boolean} Whether or not the node is a reference to the global object.
+ */
+function isGlobalThisReferenceOrGlobalWindow(scope, globalScope, node) {
+    if (scope.type === "global" && node.type === "ThisExpression") {
+        return true;
+    } else if (node.name === "window") {
+        return !isShadowed(scope, globalScope, node);
+    }
+
+    return false;
+}
 
 //------------------------------------------------------------------------------
 // Rule Definition
 //------------------------------------------------------------------------------
 
 module.exports = function(context) {
+    var globalScope;
 
     return {
 
-        "CallExpression": function(node) {
+        "Program": function () {
+            globalScope = context.getScope();
+        },
 
-            var result;
+        "CallExpression": function(node) {
+            var callee = node.callee,
+                identifierName,
+                currentScope = context.getScope();
 
             // without window.
-            if (node.callee.type === "Identifier") {
+            if (callee.type === "Identifier") {
+                identifierName = callee.name;
 
-                result = matchProhibited(node.callee.name);
-
-                if (result) {
-                    report(context, node, result);
+                if (!isShadowed(currentScope, globalScope, callee) && isProhibitedIdentifier(callee.name)) {
+                    report(context, node, identifierName);
                 }
 
-            } else if (node.callee.type === "MemberExpression" && node.callee.property.type === "Identifier") {
-
-                result = matchProhibited(node.callee.property.name);
+            } else if (callee.type === "MemberExpression" && isGlobalThisReferenceOrGlobalWindow(currentScope, globalScope, callee.object)) {
+                identifierName = getPropertyName(callee);
 
-                if (result && node.callee.object.name === "window") {
-                    report(context, node, result);
+                if (isProhibitedIdentifier(identifierName)) {
+                    report(context, node, identifierName);
                 }
-
             }
 
         }
     };
 
 };
+
+module.exports.schema = [];