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Mini Shell
Mini Shell
/**
* @fileoverview Rule to flag comparison where left part is the same as the right
* part.
* @author Ilya Volodin
*/
"use strict";
//------------------------------------------------------------------------------
// Rule Definition
//------------------------------------------------------------------------------
/** @type {import('../types').Rule.RuleModule} */
module.exports = {
meta: {
type: "problem",
docs: {
description:
"Disallow comparisons where both sides are exactly the same",
recommended: false,
url: "https://eslint.org/docs/latest/rules/no-self-compare",
},
schema: [],
messages: {
comparingToSelf: "Comparing to itself is potentially pointless.",
},
},
create(context) {
const sourceCode = context.sourceCode;
/**
* Determines whether two nodes are composed of the same tokens.
* @param {ASTNode} nodeA The first node
* @param {ASTNode} nodeB The second node
* @returns {boolean} true if the nodes have identical token representations
*/
function hasSameTokens(nodeA, nodeB) {
const tokensA = sourceCode.getTokens(nodeA);
const tokensB = sourceCode.getTokens(nodeB);
return (
tokensA.length === tokensB.length &&
tokensA.every(
(token, index) =>
token.type === tokensB[index].type &&
token.value === tokensB[index].value,
)
);
}
return {
BinaryExpression(node) {
const operators = new Set([
"===",
"==",
"!==",
"!=",
">",
"<",
">=",
"<=",
]);
if (
operators.has(node.operator) &&
hasSameTokens(node.left, node.right)
) {
context.report({ node, messageId: "comparingToSelf" });
}
},
};
},
};
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