'use strict'; const isMethodNamed = require('./utils/is-method-named.js'); const simpleArraySearchRule = require('./shared/simple-array-search-rule.js'); const {isLiteral} = require('./ast/index.js'); const MESSAGE_ID = 'prefer-includes'; const messages = { [MESSAGE_ID]: 'Use `.includes()`, rather than `.indexOf()`, when checking for existence.', }; // Ignore {_,lodash,underscore}.indexOf const ignoredVariables = new Set(['_', 'lodash', 'underscore']); const isIgnoredTarget = node => node.type === 'Identifier' && ignoredVariables.has(node.name); const isNegativeOne = node => node.type === 'UnaryExpression' && node.operator === '-' && node.argument && node.argument.type === 'Literal' && node.argument.value === 1; const isLiteralZero = node => isLiteral(node, 0); const isNegativeResult = node => ['===', '==', '<'].includes(node.operator); const getProblem = (context, node, target, argumentsNodes) => { const sourceCode = context.getSourceCode(); const memberExpressionNode = target.parent; const dotToken = sourceCode.getTokenBefore(memberExpressionNode.property); const targetSource = sourceCode.getText().slice(memberExpressionNode.range[0], dotToken.range[0]); // Strip default `fromIndex` if (isLiteralZero(argumentsNodes[1])) { argumentsNodes = argumentsNodes.slice(0, 1); } const argumentsSource = argumentsNodes.map(argument => sourceCode.getText(argument)); return { node: memberExpressionNode.property, messageId: MESSAGE_ID, fix(fixer) { const replacement = `${isNegativeResult(node) ? '!' : ''}${targetSource}.includes(${argumentsSource.join(', ')})`; return fixer.replaceText(node, replacement); }, }; }; const includesOverSomeRule = simpleArraySearchRule({ method: 'some', replacement: 'includes', }); /** @param {import('eslint').Rule.RuleContext} context */ const create = context => ({ BinaryExpression(node) { const {left, right, operator} = node; if (!isMethodNamed(left, 'indexOf')) { return; } const target = left.callee.object; if (isIgnoredTarget(target)) { return; } const {arguments: argumentsNodes} = left; // Ignore something.indexOf(foo, 0, another) if (argumentsNodes.length > 2) { return; } if ( (['!==', '!=', '>', '===', '=='].includes(operator) && isNegativeOne(right)) || (['>=', '<'].includes(operator) && isLiteralZero(right)) ) { return getProblem( context, node, target, argumentsNodes, ); } }, ...includesOverSomeRule.createListeners(context), }); /** @type {import('eslint').Rule.RuleModule} */ module.exports = { create, meta: { type: 'suggestion', docs: { description: 'Prefer `.includes()` over `.indexOf()` and `Array#some()` when checking for existence or non-existence.', }, fixable: 'code', hasSuggestions: true, messages: { ...messages, ...includesOverSomeRule.messages, }, }, };