61 lines
1.8 KiB
JavaScript
61 lines
1.8 KiB
JavaScript
/**
|
|
* @fileoverview Rule to flag comparison where left part is the same as the right
|
|
* part.
|
|
* @author Ilya Volodin
|
|
*/
|
|
|
|
"use strict";
|
|
|
|
//------------------------------------------------------------------------------
|
|
// Rule Definition
|
|
//------------------------------------------------------------------------------
|
|
|
|
module.exports = {
|
|
meta: {
|
|
type: "problem",
|
|
|
|
docs: {
|
|
description: "disallow comparisons where both sides are exactly the same",
|
|
category: "Best Practices",
|
|
recommended: false,
|
|
url: "https://eslint.org/docs/rules/no-self-compare"
|
|
},
|
|
|
|
schema: [],
|
|
|
|
messages: {
|
|
comparingToSelf: "Comparing to itself is potentially pointless."
|
|
}
|
|
},
|
|
|
|
create(context) {
|
|
const sourceCode = context.getSourceCode();
|
|
|
|
/**
|
|
* 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" });
|
|
}
|
|
}
|
|
};
|
|
|
|
}
|
|
};
|