lib/rules/jsx-key.js
/**
* @fileoverview Report missing `key` props in iterators/collection literals.
* @author Ben Mosher
*/
'use strict';
const hasProp = require('jsx-ast-utils/hasProp');
const propName = require('jsx-ast-utils/propName');
const values = require('object.values');
const docsUrl = require('../util/docsUrl');
const pragmaUtil = require('../util/pragma');
const report = require('../util/report');
const astUtil = require('../util/ast');
// ------------------------------------------------------------------------------
// Rule Definition
// ------------------------------------------------------------------------------
const defaultOptions = {
checkFragmentShorthand: false,
checkKeyMustBeforeSpread: false,
warnOnDuplicates: false,
};
const messages = {
missingIterKey: 'Missing "key" prop for element in iterator',
missingIterKeyUsePrag: 'Missing "key" prop for element in iterator. Shorthand fragment syntax does not support providing keys. Use {{reactPrag}}.{{fragPrag}} instead',
missingArrayKey: 'Missing "key" prop for element in array',
missingArrayKeyUsePrag: 'Missing "key" prop for element in array. Shorthand fragment syntax does not support providing keys. Use {{reactPrag}}.{{fragPrag}} instead',
keyBeforeSpread: '`key` prop must be placed before any `{...spread}, to avoid conflicting with React’s new JSX transform: https://reactjs.org/blog/2020/09/22/introducing-the-new-jsx-transform.html`',
nonUniqueKeys: '`key` prop must be unique',
};
/** @type {import('eslint').Rule.RuleModule} */
module.exports = {
meta: {
docs: {
description: 'Disallow missing `key` props in iterators/collection literals',
category: 'Possible Errors',
recommended: true,
url: docsUrl('jsx-key'),
},
messages,
schema: [{
type: 'object',
properties: {
checkFragmentShorthand: {
type: 'boolean',
default: defaultOptions.checkFragmentShorthand,
},
checkKeyMustBeforeSpread: {
type: 'boolean',
default: defaultOptions.checkKeyMustBeforeSpread,
},
warnOnDuplicates: {
type: 'boolean',
default: defaultOptions.warnOnDuplicates,
},
},
additionalProperties: false,
}],
},
create(context) {
const options = Object.assign({}, defaultOptions, context.options[0]);
const checkFragmentShorthand = options.checkFragmentShorthand;
const checkKeyMustBeforeSpread = options.checkKeyMustBeforeSpread;
const warnOnDuplicates = options.warnOnDuplicates;
const reactPragma = pragmaUtil.getFromContext(context);
const fragmentPragma = pragmaUtil.getFragmentFromContext(context);
function checkIteratorElement(node) {
if (node.type === 'JSXElement' && !hasProp(node.openingElement.attributes, 'key')) {
report(context, messages.missingIterKey, 'missingIterKey', {
node,
});
} else if (checkFragmentShorthand && node.type === 'JSXFragment') {
report(context, messages.missingIterKeyUsePrag, 'missingIterKeyUsePrag', {
node,
data: {
reactPrag: reactPragma,
fragPrag: fragmentPragma,
},
});
}
}
function getReturnStatements(node) {
const returnStatements = arguments[1] || [];
if (node.type === 'IfStatement') {
if (node.consequent) {
getReturnStatements(node.consequent, returnStatements);
}
if (node.alternate) {
getReturnStatements(node.alternate, returnStatements);
}
} else if (node.type === 'ReturnStatement') {
returnStatements.push(node);
} else if (Array.isArray(node.body)) {
node.body.forEach((item) => {
if (item.type === 'IfStatement') {
getReturnStatements(item, returnStatements);
}
if (item.type === 'ReturnStatement') {
returnStatements.push(item);
}
});
}
return returnStatements;
}
function isKeyAfterSpread(attributes) {
let hasFoundSpread = false;
return attributes.some((attribute) => {
if (attribute.type === 'JSXSpreadAttribute') {
hasFoundSpread = true;
return false;
}
if (attribute.type !== 'JSXAttribute') {
return false;
}
return hasFoundSpread && propName(attribute) === 'key';
});
}
/**
* Checks if the given node is a function expression or arrow function,
* and checks if there is a missing key prop in return statement's arguments
* @param {ASTNode} node
*/
function checkFunctionsBlockStatement(node) {
if (astUtil.isFunctionLikeExpression(node)) {
if (node.body.type === 'BlockStatement') {
getReturnStatements(node.body)
.filter((returnStatement) => returnStatement && returnStatement.argument)
.forEach((returnStatement) => {
checkIteratorElement(returnStatement.argument);
});
}
}
}
/**
* Checks if the given node is an arrow function that has an JSX Element or JSX Fragment in its body,
* and the JSX is missing a key prop
* @param {ASTNode} node
*/
function checkArrowFunctionWithJSX(node) {
const isArrFn = node && node.type === 'ArrowFunctionExpression';
const shouldCheckNode = (n) => n && (n.type === 'JSXElement' || n.type === 'JSXFragment');
if (isArrFn && shouldCheckNode(node.body)) {
checkIteratorElement(node.body);
}
if (node.body.type === 'ConditionalExpression') {
if (shouldCheckNode(node.body.consequent)) {
checkIteratorElement(node.body.consequent);
}
if (shouldCheckNode(node.body.alternate)) {
checkIteratorElement(node.body.alternate);
}
} else if (node.body.type === 'LogicalExpression' && shouldCheckNode(node.body.right)) {
checkIteratorElement(node.body.right);
}
}
const childrenToArraySelector = `:matches(
CallExpression
[callee.object.object.name=${reactPragma}]
[callee.object.property.name=Children]
[callee.property.name=toArray],
CallExpression
[callee.object.name=Children]
[callee.property.name=toArray]
)`.replace(/\s/g, '');
let isWithinChildrenToArray = false;
const seen = new WeakSet();
return {
[childrenToArraySelector]() {
isWithinChildrenToArray = true;
},
[`${childrenToArraySelector}:exit`]() {
isWithinChildrenToArray = false;
},
'ArrayExpression, JSXElement > JSXElement'(node) {
if (isWithinChildrenToArray) {
return;
}
const jsx = (node.type === 'ArrayExpression' ? node.elements : node.parent.children).filter((x) => x && x.type === 'JSXElement');
if (jsx.length === 0) {
return;
}
const map = {};
jsx.forEach((element) => {
const attrs = element.openingElement.attributes;
const keys = attrs.filter((x) => x.name && x.name.name === 'key');
if (keys.length === 0) {
if (node.type === 'ArrayExpression') {
report(context, messages.missingArrayKey, 'missingArrayKey', {
node: element,
});
}
} else {
keys.forEach((attr) => {
const value = context.getSourceCode().getText(attr.value);
if (!map[value]) { map[value] = []; }
map[value].push(attr);
if (checkKeyMustBeforeSpread && isKeyAfterSpread(attrs)) {
report(context, messages.keyBeforeSpread, 'keyBeforeSpread', {
node: node.type === 'ArrayExpression' ? node : node.parent,
});
}
});
}
});
if (warnOnDuplicates) {
values(map).filter((v) => v.length > 1).forEach((v) => {
v.forEach((n) => {
if (!seen.has(n)) {
seen.add(n);
report(context, messages.nonUniqueKeys, 'nonUniqueKeys', {
node: n,
});
}
});
});
}
},
JSXFragment(node) {
if (!checkFragmentShorthand || isWithinChildrenToArray) {
return;
}
if (node.parent.type === 'ArrayExpression') {
report(context, messages.missingArrayKeyUsePrag, 'missingArrayKeyUsePrag', {
node,
data: {
reactPrag: reactPragma,
fragPrag: fragmentPragma,
},
});
}
},
// Array.prototype.map
// eslint-disable-next-line no-multi-str
'CallExpression[callee.type="MemberExpression"][callee.property.name="map"],\
CallExpression[callee.type="OptionalMemberExpression"][callee.property.name="map"],\
OptionalCallExpression[callee.type="MemberExpression"][callee.property.name="map"],\
OptionalCallExpression[callee.type="OptionalMemberExpression"][callee.property.name="map"]'(node) {
if (isWithinChildrenToArray) {
return;
}
const fn = node.arguments.length > 0 && node.arguments[0];
if (!fn || !astUtil.isFunctionLikeExpression(fn)) {
return;
}
checkArrowFunctionWithJSX(fn);
checkFunctionsBlockStatement(fn);
},
// Array.from
'CallExpression[callee.type="MemberExpression"][callee.property.name="from"]'(node) {
if (isWithinChildrenToArray) {
return;
}
const fn = node.arguments.length > 1 && node.arguments[1];
if (!astUtil.isFunctionLikeExpression(fn)) {
return;
}
checkArrowFunctionWithJSX(fn);
checkFunctionsBlockStatement(fn);
},
};
},
};