1 | /**
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2 | * @fileoverview Rule to flag when return statement contains assignment
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3 | * @author Ilya Volodin
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4 | */
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5 | ;
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6 |
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7 | //------------------------------------------------------------------------------
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8 | // Requirements
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9 | //------------------------------------------------------------------------------
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10 |
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11 | const astUtils = require("../ast-utils");
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12 |
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13 | //------------------------------------------------------------------------------
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14 | // Helpers
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15 | //------------------------------------------------------------------------------
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16 |
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17 | const SENTINEL_TYPE = /^(?:[a-zA-Z]+?Statement|ArrowFunctionExpression|FunctionExpression|ClassExpression)$/;
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18 |
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19 | //------------------------------------------------------------------------------
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20 | // Rule Definition
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21 | //------------------------------------------------------------------------------
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22 |
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23 | module.exports = {
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24 | meta: {
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25 | docs: {
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26 | description: "disallow assignment operators in `return` statements",
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27 | category: "Best Practices",
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28 | recommended: false,
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29 | url: "https://eslint.org/docs/rules/no-return-assign"
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30 | },
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31 |
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32 | schema: [
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33 | {
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34 | enum: ["except-parens", "always"]
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35 | }
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36 | ]
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37 | },
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38 |
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39 | create(context) {
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40 | const always = (context.options[0] || "except-parens") !== "except-parens";
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41 | const sourceCode = context.getSourceCode();
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42 |
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43 | return {
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44 | AssignmentExpression(node) {
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45 | if (!always && astUtils.isParenthesised(sourceCode, node)) {
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46 | return;
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47 | }
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48 |
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49 | let currentChild = node;
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50 | let parent = currentChild.parent;
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51 |
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52 | // Find ReturnStatement or ArrowFunctionExpression in ancestors.
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53 | while (parent && !SENTINEL_TYPE.test(parent.type)) {
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54 | currentChild = parent;
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55 | parent = parent.parent;
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56 | }
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57 |
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58 | // Reports.
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59 | if (parent && parent.type === "ReturnStatement") {
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60 | context.report({
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61 | node: parent,
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62 | message: "Return statement should not contain assignment."
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63 | });
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64 | } else if (parent && parent.type === "ArrowFunctionExpression" && parent.body === currentChild) {
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65 | context.report({
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66 | node: parent,
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67 | message: "Arrow function should not return assignment."
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68 | });
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69 | }
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70 | }
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71 | };
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72 | }
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73 | };
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