You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
141 lines
4.6 KiB
141 lines
4.6 KiB
/**
|
|
* @fileoverview Rule to flag comparisons to the value NaN
|
|
* @author James Allardice
|
|
*/
|
|
|
|
"use strict";
|
|
|
|
//------------------------------------------------------------------------------
|
|
// Requirements
|
|
//------------------------------------------------------------------------------
|
|
|
|
const astUtils = require("./utils/ast-utils");
|
|
|
|
//------------------------------------------------------------------------------
|
|
// Helpers
|
|
//------------------------------------------------------------------------------
|
|
|
|
/**
|
|
* Determines if the given node is a NaN `Identifier` node.
|
|
* @param {ASTNode|null} node The node to check.
|
|
* @returns {boolean} `true` if the node is 'NaN' identifier.
|
|
*/
|
|
function isNaNIdentifier(node) {
|
|
return Boolean(node) && (
|
|
astUtils.isSpecificId(node, "NaN") ||
|
|
astUtils.isSpecificMemberAccess(node, "Number", "NaN")
|
|
);
|
|
}
|
|
|
|
//------------------------------------------------------------------------------
|
|
// Rule Definition
|
|
//------------------------------------------------------------------------------
|
|
|
|
/** @type {import('../shared/types').Rule} */
|
|
module.exports = {
|
|
meta: {
|
|
type: "problem",
|
|
|
|
docs: {
|
|
description: "Require calls to `isNaN()` when checking for `NaN`",
|
|
recommended: true,
|
|
url: "https://eslint.org/docs/latest/rules/use-isnan"
|
|
},
|
|
|
|
schema: [
|
|
{
|
|
type: "object",
|
|
properties: {
|
|
enforceForSwitchCase: {
|
|
type: "boolean",
|
|
default: true
|
|
},
|
|
enforceForIndexOf: {
|
|
type: "boolean",
|
|
default: false
|
|
}
|
|
},
|
|
additionalProperties: false
|
|
}
|
|
],
|
|
|
|
messages: {
|
|
comparisonWithNaN: "Use the isNaN function to compare with NaN.",
|
|
switchNaN: "'switch(NaN)' can never match a case clause. Use Number.isNaN instead of the switch.",
|
|
caseNaN: "'case NaN' can never match. Use Number.isNaN before the switch.",
|
|
indexOfNaN: "Array prototype method '{{ methodName }}' cannot find NaN."
|
|
}
|
|
},
|
|
|
|
create(context) {
|
|
|
|
const enforceForSwitchCase = !context.options[0] || context.options[0].enforceForSwitchCase;
|
|
const enforceForIndexOf = context.options[0] && context.options[0].enforceForIndexOf;
|
|
|
|
/**
|
|
* Checks the given `BinaryExpression` node for `foo === NaN` and other comparisons.
|
|
* @param {ASTNode} node The node to check.
|
|
* @returns {void}
|
|
*/
|
|
function checkBinaryExpression(node) {
|
|
if (
|
|
/^(?:[<>]|[!=]=)=?$/u.test(node.operator) &&
|
|
(isNaNIdentifier(node.left) || isNaNIdentifier(node.right))
|
|
) {
|
|
context.report({ node, messageId: "comparisonWithNaN" });
|
|
}
|
|
}
|
|
|
|
/**
|
|
* Checks the discriminant and all case clauses of the given `SwitchStatement` node for `switch(NaN)` and `case NaN:`
|
|
* @param {ASTNode} node The node to check.
|
|
* @returns {void}
|
|
*/
|
|
function checkSwitchStatement(node) {
|
|
if (isNaNIdentifier(node.discriminant)) {
|
|
context.report({ node, messageId: "switchNaN" });
|
|
}
|
|
|
|
for (const switchCase of node.cases) {
|
|
if (isNaNIdentifier(switchCase.test)) {
|
|
context.report({ node: switchCase, messageId: "caseNaN" });
|
|
}
|
|
}
|
|
}
|
|
|
|
/**
|
|
* Checks the given `CallExpression` node for `.indexOf(NaN)` and `.lastIndexOf(NaN)`.
|
|
* @param {ASTNode} node The node to check.
|
|
* @returns {void}
|
|
*/
|
|
function checkCallExpression(node) {
|
|
const callee = astUtils.skipChainExpression(node.callee);
|
|
|
|
if (callee.type === "MemberExpression") {
|
|
const methodName = astUtils.getStaticPropertyName(callee);
|
|
|
|
if (
|
|
(methodName === "indexOf" || methodName === "lastIndexOf") &&
|
|
node.arguments.length === 1 &&
|
|
isNaNIdentifier(node.arguments[0])
|
|
) {
|
|
context.report({ node, messageId: "indexOfNaN", data: { methodName } });
|
|
}
|
|
}
|
|
}
|
|
|
|
const listeners = {
|
|
BinaryExpression: checkBinaryExpression
|
|
};
|
|
|
|
if (enforceForSwitchCase) {
|
|
listeners.SwitchStatement = checkSwitchStatement;
|
|
}
|
|
|
|
if (enforceForIndexOf) {
|
|
listeners.CallExpression = checkCallExpression;
|
|
}
|
|
|
|
return listeners;
|
|
}
|
|
};
|