| /** |
| * @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: [] |
| }, |
| |
| 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, message: "Comparing to itself is potentially pointless." }); |
| } |
| } |
| }; |
| |
| } |
| }; |