2 * @fileoverview Rule to disallow mixed binary operators.
3 * @author Toru Nagashima
8 //------------------------------------------------------------------------------
10 //------------------------------------------------------------------------------
12 const astUtils = require("./utils/ast-utils.js");
14 //------------------------------------------------------------------------------
16 //------------------------------------------------------------------------------
18 const ARITHMETIC_OPERATORS = ["+", "-", "*", "/", "%", "**"];
19 const BITWISE_OPERATORS = ["&", "|", "^", "~", "<<", ">>", ">>>"];
20 const COMPARISON_OPERATORS = ["==", "!=", "===", "!==", ">", ">=", "<", "<="];
21 const LOGICAL_OPERATORS = ["&&", "||"];
22 const RELATIONAL_OPERATORS = ["in", "instanceof"];
23 const TERNARY_OPERATOR = ["?:"];
24 const COALESCE_OPERATOR = ["??"];
25 const ALL_OPERATORS = [].concat(
34 const DEFAULT_GROUPS = [
41 const TARGET_NODE_TYPE = /^(?:Binary|Logical|Conditional)Expression$/u;
45 * @param {Object|undefined} options A options object to normalize.
46 * @returns {Object} Normalized option object.
48 function normalizeOptions(options = {}) {
49 const hasGroups = options.groups && options.groups.length > 0;
50 const groups = hasGroups ? options.groups : DEFAULT_GROUPS;
51 const allowSamePrecedence = options.allowSamePrecedence !== false;
60 * Checks whether any group which includes both given operator exists or not.
61 * @param {Array.<string[]>} groups A list of groups to check.
62 * @param {string} left An operator.
63 * @param {string} right Another operator.
64 * @returns {boolean} `true` if such group existed.
66 function includesBothInAGroup(groups, left, right) {
67 return groups.some(group => group.indexOf(left) !== -1 && group.indexOf(right) !== -1);
71 * Checks whether the given node is a conditional expression and returns the test node else the left node.
72 * @param {ASTNode} node A node which can be a BinaryExpression or a LogicalExpression node.
73 * This parent node can be BinaryExpression, LogicalExpression
74 * , or a ConditionalExpression node
75 * @returns {ASTNode} node the appropriate node(left or test).
77 function getChildNode(node) {
78 return node.type === "ConditionalExpression" ? node.test : node.left;
81 //------------------------------------------------------------------------------
83 //------------------------------------------------------------------------------
90 description: "disallow mixed binary operators",
91 category: "Stylistic Issues",
93 url: "https://eslint.org/docs/rules/no-mixed-operators"
104 items: { enum: ALL_OPERATORS },
110 allowSamePrecedence: {
115 additionalProperties: false
120 unexpectedMixedOperator: "Unexpected mix of '{{leftOperator}}' and '{{rightOperator}}'. Use parentheses to clarify the intended order of operations."
125 const sourceCode = context.getSourceCode();
126 const options = normalizeOptions(context.options[0]);
129 * Checks whether a given node should be ignored by options or not.
130 * @param {ASTNode} node A node to check. This is a BinaryExpression
131 * node or a LogicalExpression node. This parent node is one of
133 * @returns {boolean} `true` if the node should be ignored.
135 function shouldIgnore(node) {
137 const b = node.parent;
140 !includesBothInAGroup(options.groups, a.operator, b.type === "ConditionalExpression" ? "?:" : b.operator) ||
142 options.allowSamePrecedence &&
143 astUtils.getPrecedence(a) === astUtils.getPrecedence(b)
149 * Checks whether the operator of a given node is mixed with parent
150 * node's operator or not.
151 * @param {ASTNode} node A node to check. This is a BinaryExpression
152 * node or a LogicalExpression node. This parent node is one of
154 * @returns {boolean} `true` if the node was mixed.
156 function isMixedWithParent(node) {
159 node.operator !== node.parent.operator &&
160 !astUtils.isParenthesised(sourceCode, node)
165 * Gets the operator token of a given node.
166 * @param {ASTNode} node A node to check. This is a BinaryExpression
167 * node or a LogicalExpression node.
168 * @returns {Token} The operator token of the node.
170 function getOperatorToken(node) {
171 return sourceCode.getTokenAfter(getChildNode(node), astUtils.isNotClosingParenToken);
175 * Reports both the operator of a given node and the operator of the
177 * @param {ASTNode} node A node to check. This is a BinaryExpression
178 * node or a LogicalExpression node. This parent node is one of
182 function reportBothOperators(node) {
183 const parent = node.parent;
184 const left = (getChildNode(parent) === node) ? node : parent;
185 const right = (getChildNode(parent) !== node) ? node : parent;
187 leftOperator: left.operator || "?:",
188 rightOperator: right.operator || "?:"
193 loc: getOperatorToken(left).loc,
194 messageId: "unexpectedMixedOperator",
199 loc: getOperatorToken(right).loc,
200 messageId: "unexpectedMixedOperator",
206 * Checks between the operator of this node and the operator of the
208 * @param {ASTNode} node A node to check.
211 function check(node) {
213 TARGET_NODE_TYPE.test(node.parent.type) &&
214 isMixedWithParent(node) &&
217 reportBothOperators(node);
222 BinaryExpression: check,
223 LogicalExpression: check