1 | /**
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2 | * @fileoverview Rule to enforce a maximum number of nested callbacks.
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3 | * @author Ian Christian Myers
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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 | //------------------------------------------------------------------------------
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9 | // Rule Definition
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10 | //------------------------------------------------------------------------------
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11 |
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12 | module.exports = {
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13 | meta: {
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14 | type: "suggestion",
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15 |
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16 | docs: {
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17 | description: "enforce a maximum depth that callbacks can be nested",
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18 | category: "Stylistic Issues",
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19 | recommended: false,
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20 | url: "https://eslint.org/docs/rules/max-nested-callbacks"
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21 | },
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22 |
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23 | schema: [
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24 | {
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25 | oneOf: [
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26 | {
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27 | type: "integer",
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28 | minimum: 0
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29 | },
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30 | {
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31 | type: "object",
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32 | properties: {
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33 | maximum: {
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34 | type: "integer",
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35 | minimum: 0
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36 | },
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37 | max: {
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38 | type: "integer",
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39 | minimum: 0
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40 | }
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41 | },
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42 | additionalProperties: false
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43 | }
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44 | ]
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45 | }
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46 | ],
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47 | messages: {
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48 | exceed: "Too many nested callbacks ({{num}}). Maximum allowed is {{max}}."
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49 | }
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50 | },
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51 |
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52 | create(context) {
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53 |
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54 | //--------------------------------------------------------------------------
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55 | // Constants
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56 | //--------------------------------------------------------------------------
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57 | const option = context.options[0];
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58 | let THRESHOLD = 10;
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59 |
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60 | if (
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61 | typeof option === "object" &&
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62 | (Object.prototype.hasOwnProperty.call(option, "maximum") || Object.prototype.hasOwnProperty.call(option, "max"))
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63 | ) {
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64 | THRESHOLD = option.maximum || option.max;
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65 | } else if (typeof option === "number") {
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66 | THRESHOLD = option;
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67 | }
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68 |
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69 | //--------------------------------------------------------------------------
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70 | // Helpers
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71 | //--------------------------------------------------------------------------
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72 |
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73 | const callbackStack = [];
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74 |
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75 | /**
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76 | * Checks a given function node for too many callbacks.
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77 | * @param {ASTNode} node The node to check.
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78 | * @returns {void}
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79 | * @private
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80 | */
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81 | function checkFunction(node) {
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82 | const parent = node.parent;
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83 |
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84 | if (parent.type === "CallExpression") {
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85 | callbackStack.push(node);
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86 | }
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87 |
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88 | if (callbackStack.length > THRESHOLD) {
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89 | const opts = { num: callbackStack.length, max: THRESHOLD };
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90 |
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91 | context.report({ node, messageId: "exceed", data: opts });
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92 | }
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93 | }
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94 |
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95 | /**
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96 | * Pops the call stack.
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97 | * @returns {void}
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98 | * @private
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99 | */
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100 | function popStack() {
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101 | callbackStack.pop();
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102 | }
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103 |
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104 | //--------------------------------------------------------------------------
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105 | // Public API
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106 | //--------------------------------------------------------------------------
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107 |
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108 | return {
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109 | ArrowFunctionExpression: checkFunction,
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110 | "ArrowFunctionExpression:exit": popStack,
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111 |
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112 | FunctionExpression: checkFunction,
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113 | "FunctionExpression:exit": popStack
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114 | };
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115 |
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116 | }
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117 | };
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