/
no-null.js
121 lines (107 loc) · 2.97 KB
/
no-null.js
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'use strict';
const {
not,
methodCallSelector,
callExpressionSelector,
} = require('./selectors/index.js');
const ERROR_MESSAGE_ID = 'error';
const SUGGESTION_REPLACE_MESSAGE_ID = 'replace';
const SUGGESTION_REMOVE_MESSAGE_ID = 'remove';
const messages = {
[ERROR_MESSAGE_ID]: 'Use `undefined` instead of `null`.',
[SUGGESTION_REPLACE_MESSAGE_ID]: 'Replace `null` with `undefined`.',
[SUGGESTION_REMOVE_MESSAGE_ID]: 'Remove `null`.',
};
const selector = [
'Literal',
'[raw="null"]',
not([
// `Object.create(null)`, `Object.create(null, foo)`
`${methodCallSelector({object: 'Object', method: 'create', minimumArguments: 1, maximumArguments: 2})} > .arguments:first-child`,
// `useRef(null)`
`${callExpressionSelector({name: 'useRef', argumentsLength: 1})} > .arguments:first-child`,
// `React.useRef(null)`
`${methodCallSelector({object: 'React', method: 'useRef', argumentsLength: 1})} > .arguments:first-child`,
// `foo.insertBefore(bar, null)`
`${methodCallSelector({method: 'insertBefore', argumentsLength: 2})}[arguments.0.type!="SpreadElement"] > .arguments:nth-child(2)`,
]),
].join('');
const isLooseEqual = node => node.type === 'BinaryExpression' && ['==', '!='].includes(node.operator);
const isStrictEqual = node => node.type === 'BinaryExpression' && ['===', '!=='].includes(node.operator);
const create = context => {
const {checkStrictEquality} = {
checkStrictEquality: false,
...context.options[0],
};
return {
[selector]: node => {
const {parent} = node;
if (!checkStrictEquality && isStrictEqual(parent)) {
return;
}
const problem = {
node,
messageId: ERROR_MESSAGE_ID,
};
const useUndefinedFix = fixer => fixer.replaceText(node, 'undefined');
if (isLooseEqual(parent)) {
problem.fix = useUndefinedFix;
return problem;
}
const useUndefinedSuggestion = {
messageId: SUGGESTION_REPLACE_MESSAGE_ID,
fix: useUndefinedFix,
};
if (parent.type === 'ReturnStatement' && parent.argument === node) {
problem.suggest = [
{
messageId: SUGGESTION_REMOVE_MESSAGE_ID,
fix: fixer => fixer.remove(node),
},
useUndefinedSuggestion,
];
return problem;
}
if (parent.type === 'VariableDeclarator' && parent.init === node && parent.parent.kind !== 'const') {
problem.suggest = [
{
messageId: SUGGESTION_REMOVE_MESSAGE_ID,
fix: fixer => fixer.removeRange([parent.id.range[1], node.range[1]]),
},
useUndefinedSuggestion,
];
return problem;
}
problem.suggest = [useUndefinedSuggestion];
return problem;
},
};
};
const schema = [
{
type: 'object',
additionalProperties: false,
properties: {
checkStrictEquality: {
type: 'boolean',
default: false,
},
},
},
];
/**
* @type {import('eslint').Rule.RuleModule}
*/
module.exports = {
create,
meta: {
type: 'suggestion',
docs: {
description: 'Disallow the use of the `null` literal.',
},
fixable: 'code',
hasSuggestions: true,
schema,
messages,
},
};