eslint-plugin-lodash/src/rules/prefer-reject.js

Lodash specific linting rules for ESLint

/**
 * @fileoverview Rule to check if a call to filter should be a call to reject
 */
'use strict'

//------------------------------------------------------------------------------
// Rule Definition
//------------------------------------------------------------------------------

const getDocsUrl = require('../util/getDocsUrl')

module.exports = {
    meta: {
        type: 'problem',
        docs: {
            url: getDocsUrl('prefer-reject')
        },
        schema: [{
            type: 'integer'
        }]
    },

    create(context) {
        const {isCallToLodashMethod, getLodashMethodVisitors} = require('../util/lodashUtil')
        const {getValueReturnedInFirstStatement, getFirstParamName, isNegationOfMemberOf, isNotEqEqToMemberOf} = require('../util/astUtil')
        const {isAliasOfMethod} = require('../util/methodDataUtil')
        const DEFAULT_MAX_PROPERTY_PATH_LENGTH = 3
        const maxLength = parseInt(context.options[0], 10) || DEFAULT_MAX_PROPERTY_PATH_LENGTH

        function isNegativeExpressionFunction(func, lodashContext) {
            const returnValue = getValueReturnedInFirstStatement(func)
            const firstParamName = getFirstParamName(func)
            return isNegationOfMemberOf(returnValue, firstParamName, {maxLength}) ||
                isNotEqEqToMemberOf(returnValue, firstParamName, {maxLength}) || isCallToLodashMethod(func, 'negate', lodashContext)
        }

        return getLodashMethodVisitors(context, (node, iteratee, {method, version, lodashContext}) => {
            if (isAliasOfMethod(version, 'filter', method) && isNegativeExpressionFunction(iteratee, lodashContext)) {
                context.report({node, message: 'Prefer _.reject over negative condition'})
            }
        })
    }
}