no-alert.js
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/**
* @fileoverview Rule to flag use of alert, confirm, prompt
* @author Nicholas C. Zakas
*/
"use strict";
//------------------------------------------------------------------------------
// Requirements
//------------------------------------------------------------------------------
const getPropertyName = require("../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)$/.test(name);
}
/**
* 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 });
}
/**
* Finds the escope 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 {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) {
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 {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 = {
meta: {
docs: {
description: "disallow the use of `alert`, `confirm`, and `prompt`",
category: "Best Practices",
recommended: false
},
schema: []
},
create(context) {
let globalScope;
return {
Program() {
globalScope = context.getScope();
},
CallExpression(node) {
const callee = node.callee,
currentScope = context.getScope();
// without window.
if (callee.type === "Identifier") {
const identifierName = callee.name;
if (!isShadowed(currentScope, globalScope, callee) && isProhibitedIdentifier(callee.name)) {
report(context, node, identifierName);
}
} else if (callee.type === "MemberExpression" && isGlobalThisReferenceOrGlobalWindow(currentScope, globalScope, callee.object)) {
const identifierName = getPropertyName(callee);
if (isProhibitedIdentifier(identifierName)) {
report(context, node, identifierName);
}
}
}
};
}
};