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/**
* @fileoverview Rule to flag use of implied eval via setTimeout and setInterval
* @author James Allardice
*/
"use strict";
//------------------------------------------------------------------------------
// Requirements
//------------------------------------------------------------------------------
const astUtils = require("./utils/ast-utils");
const { getStaticValue } = require("@eslint-community/eslint-utils");
//------------------------------------------------------------------------------
// Rule Definition
//------------------------------------------------------------------------------
/** @type {import('../shared/types').Rule} */
module.exports = {
meta: {
type: "suggestion",
docs: {
description: "Disallow the use of `eval()`-like methods",
recommended: false,
url: "https://eslint.org/docs/latest/rules/no-implied-eval"
},
schema: [],
messages: {
impliedEval: "Implied eval. Consider passing a function instead of a string."
}
},
create(context) {
const GLOBAL_CANDIDATES = Object.freeze(["global", "window", "globalThis"]);
const EVAL_LIKE_FUNC_PATTERN = /^(?:set(?:Interval|Timeout)|execScript)$/u;
const sourceCode = context.sourceCode;
/**
* Checks whether a node is evaluated as a string or not.
* @param {ASTNode} node A node to check.
* @returns {boolean} True if the node is evaluated as a string.
*/
function isEvaluatedString(node) {
if (
(node.type === "Literal" && typeof node.value === "string") ||
node.type === "TemplateLiteral"
) {
return true;
}
if (node.type === "BinaryExpression" && node.operator === "+") {
return isEvaluatedString(node.left) || isEvaluatedString(node.right);
}
return false;
}
/**
* Reports if the `CallExpression` node has evaluated argument.
* @param {ASTNode} node A CallExpression to check.
* @returns {void}
*/
function reportImpliedEvalCallExpression(node) {
const [firstArgument] = node.arguments;
if (firstArgument) {
const staticValue = getStaticValue(firstArgument, sourceCode.getScope(node));
const isStaticString = staticValue && typeof staticValue.value === "string";
const isString = isStaticString || isEvaluatedString(firstArgument);
if (isString) {
context.report({
node,
messageId: "impliedEval"
});
}
}
}
/**
* Reports calls of `implied eval` via the global references.
* @param {Variable} globalVar A global variable to check.
* @returns {void}
*/
function reportImpliedEvalViaGlobal(globalVar) {
const { references, name } = globalVar;
references.forEach(ref => {
const identifier = ref.identifier;
let node = identifier.parent;
while (astUtils.isSpecificMemberAccess(node, null, name)) {
node = node.parent;
}
if (astUtils.isSpecificMemberAccess(node, null, EVAL_LIKE_FUNC_PATTERN)) {
const calleeNode = node.parent.type === "ChainExpression" ? node.parent : node;
const parent = calleeNode.parent;
if (parent.type === "CallExpression" && parent.callee === calleeNode) {
reportImpliedEvalCallExpression(parent);
}
}
});
}
//--------------------------------------------------------------------------
// Public
//--------------------------------------------------------------------------
return {
CallExpression(node) {
if (astUtils.isSpecificId(node.callee, EVAL_LIKE_FUNC_PATTERN)) {
reportImpliedEvalCallExpression(node);
}
},
"Program:exit"(node) {
const globalScope = sourceCode.getScope(node);
GLOBAL_CANDIDATES
.map(candidate => astUtils.getVariableByName(globalScope, candidate))
.filter(globalVar => !!globalVar && globalVar.defs.length === 0)
.forEach(reportImpliedEvalViaGlobal);
}
};
}
};