Skip to content
Permalink
9bfb9ba527
Switch branches/tags

Name already in use

A tag already exists with the provided branch name. Many Git commands accept both tag and branch names, so creating this branch may cause unexpected behavior. Are you sure you want to create this branch?
Go to file
 
 
Cannot retrieve contributors at this time
60 lines (47 sloc) 1.81 KB
/**
* @fileoverview Rule to flag comparison where left part is the same as the right
* part.
* @author Ilya Volodin
*/
"use strict";
//------------------------------------------------------------------------------
// Rule Definition
//------------------------------------------------------------------------------
/** @type {import('../shared/types').Rule} */
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" });
}
}
};
}
};