no-unused-expressions.js

/**
 * @fileoverview Flag expressions in statement position that do not side effect
 * @author Michael Ficarra
 */
"use strict";

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

/**
 * Returns `true`.
 * @returns {boolean} `true`.
 */
function alwaysTrue() {
    return true;
}

/**
 * Returns `false`.
 * @returns {boolean} `false`.
 */
function alwaysFalse() {
    return false;
}

module.exports = {
    meta: {
        type: "suggestion",

        docs: {
            description: "disallow unused expressions",
            category: "Best Practices",
            recommended: false,
            url: "https://eslint.org/docs/rules/no-unused-expressions"
        },

        schema: [
            {
                type: "object",
                properties: {
                    allowShortCircuit: {
                        type: "boolean",
                        default: false
                    },
                    allowTernary: {
                        type: "boolean",
                        default: false
                    },
                    allowTaggedTemplates: {
                        type: "boolean",
                        default: false
                    },
                    enforceForJSX: {
                        type: "boolean",
                        default: false
                    }
                },
                additionalProperties: false
            }
        ],

        messages: {
            unusedExpression: "Expected an assignment or function call and instead saw an expression."
        }
    },

    create(context) {
        const config = context.options[0] || {},
            allowShortCircuit = config.allowShortCircuit || false,