1 | /**
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2 | * @fileoverview A rule to warn against using arrow functions when they could be
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3 | * confused with comparisons
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4 | * @author Jxck <https://github.com/Jxck>
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5 | */
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6 |
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7 | ;
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8 |
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9 | const astUtils = require("./utils/ast-utils.js");
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10 |
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11 | //------------------------------------------------------------------------------
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12 | // Helpers
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13 | //------------------------------------------------------------------------------
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14 |
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15 | /**
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16 | * Checks whether or not a node is a conditional expression.
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17 | * @param {ASTNode} node node to test
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18 | * @returns {boolean} `true` if the node is a conditional expression.
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19 | */
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20 | function isConditional(node) {
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21 | return node && node.type === "ConditionalExpression";
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22 | }
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23 |
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24 | //------------------------------------------------------------------------------
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25 | // Rule Definition
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26 | //------------------------------------------------------------------------------
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27 |
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28 | module.exports = {
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29 | meta: {
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30 | type: "suggestion",
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31 |
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32 | docs: {
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33 | description: "disallow arrow functions where they could be confused with comparisons",
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34 | category: "ECMAScript 6",
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35 | recommended: false,
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36 | url: "https://eslint.org/docs/rules/no-confusing-arrow"
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37 | },
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38 |
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39 | fixable: "code",
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40 |
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41 | schema: [{
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42 | type: "object",
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43 | properties: {
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44 | allowParens: { type: "boolean", default: true }
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45 | },
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46 | additionalProperties: false
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47 | }],
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48 |
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49 | messages: {
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50 | confusing: "Arrow function used ambiguously with a conditional expression."
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51 | }
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52 | },
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53 |
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54 | create(context) {
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55 | const config = context.options[0] || {};
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56 | const allowParens = config.allowParens || (config.allowParens === void 0);
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57 | const sourceCode = context.getSourceCode();
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58 |
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59 |
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60 | /**
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61 | * Reports if an arrow function contains an ambiguous conditional.
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62 | * @param {ASTNode} node A node to check and report.
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63 | * @returns {void}
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64 | */
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65 | function checkArrowFunc(node) {
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66 | const body = node.body;
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67 |
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68 | if (isConditional(body) && !(allowParens && astUtils.isParenthesised(sourceCode, body))) {
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69 | context.report({
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70 | node,
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71 | messageId: "confusing",
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72 | fix(fixer) {
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73 |
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74 | // if `allowParens` is not set to true don't bother wrapping in parens
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75 | return allowParens && fixer.replaceText(node.body, `(${sourceCode.getText(node.body)})`);
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76 | }
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77 | });
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78 | }
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79 | }
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80 |
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81 | return {
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82 | ArrowFunctionExpression: checkArrowFunc
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83 | };
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84 | }
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85 | };
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