--- /dev/null
+/**
+ * @fileoverview Rule to flag use of alert, confirm, prompt
+ * @author Nicholas C. Zakas
+ */
+"use strict";
+
+//------------------------------------------------------------------------------
+// Requirements
+//------------------------------------------------------------------------------
+
+const getPropertyName = require("./utils/ast-utils").getStaticPropertyName;
+
+//------------------------------------------------------------------------------
+// Helpers
+//------------------------------------------------------------------------------
+
+/**
+ * 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)$/u.test(name);
+}
+
+/**
+ * Finds the eslint-scope reference in the given scope.
+ * @param {Object} scope The scope to search.
+ * @param {ASTNode} node The identifier node.
+ * @returns {Reference|null} Returns the found reference or null if none were found.
+ */
+function findReference(scope, node) {
+ const references = scope.references.filter(reference => reference.identifier.range[0] === node.range[0] &&
+ reference.identifier.range[1] === node.range[1]);
+
+ if (references.length === 1) {
+ return references[0];
+ }
+ return null;
+}
+
+/**
+ * Checks if the given identifier node is shadowed in the given scope.
+ * @param {Object} scope The current scope.
+ * @param {string} node The identifier node to check
+ * @returns {boolean} Whether or not the name is shadowed.
+ */
+function isShadowed(scope, node) {
+ const reference = findReference(scope, node);
+
+ return reference && reference.resolved && reference.resolved.defs.length > 0;
+}
+
+/**
+ * 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 {string} node The identifier node to check
+ * @returns {boolean} Whether or not the node is a reference to the global object.
+ */
+function isGlobalThisReferenceOrGlobalWindow(scope, node) {
+ if (scope.type === "global" && node.type === "ThisExpression") {
+ return true;
+ }
+ if (node.name === "window") {
+ return !isShadowed(scope, node);
+ }
+
+ return false;
+}
+
+//------------------------------------------------------------------------------
+// Rule Definition
+//------------------------------------------------------------------------------
+
+module.exports = {
+ meta: {
+ type: "suggestion",
+
+ docs: {
+ description: "disallow the use of `alert`, `confirm`, and `prompt`",
+ category: "Best Practices",
+ recommended: false,
+ url: "https://eslint.org/docs/rules/no-alert"
+ },
+
+ schema: [],
+
+ messages: {
+ unexpected: "Unexpected {{name}}."
+ }
+ },
+
+ create(context) {
+ return {
+ CallExpression(node) {
+ const callee = node.callee,
+ currentScope = context.getScope();
+
+ // without window.
+ if (callee.type === "Identifier") {
+ const name = callee.name;
+
+ if (!isShadowed(currentScope, callee) && isProhibitedIdentifier(callee.name)) {
+ context.report({
+ node,
+ messageId: "unexpected",
+ data: { name }
+ });
+ }
+
+ } else if (callee.type === "MemberExpression" && isGlobalThisReferenceOrGlobalWindow(currentScope, callee.object)) {
+ const name = getPropertyName(callee);
+
+ if (isProhibitedIdentifier(name)) {
+ context.report({
+ node,
+ messageId: "unexpected",
+ data: { name }
+ });
+ }
+ }
+
+ }
+ };
+
+ }
+};