no-alert.js
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/**
* @fileoverview Rule to flag use of alert, confirm, prompt
* @author Nicholas C. Zakas
*/
"use strict";
//------------------------------------------------------------------------------
// Requirements
//------------------------------------------------------------------------------
const {
getStaticPropertyName: getPropertyName,
getVariableByName,
skipChainExpression
} = require("./utils/ast-utils");
//------------------------------------------------------------------------------
// 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.type === "Identifier" &&
(
node.name === "window" ||
(node.name === "globalThis" && getVariableByName(scope, "globalThis"))
)
) {
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 = skipChainExpression(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 }
});
}
}
}
};
}
};