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443c22e | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 | /**
* @fileoverview Rule to flag statements that use != and == instead of !== and ===
* @author Nicholas C. Zakas
*/
"use strict";
//------------------------------------------------------------------------------
// Requirements
//------------------------------------------------------------------------------
const astUtils = require("./utils/ast-utils");
//------------------------------------------------------------------------------
// Rule Definition
//------------------------------------------------------------------------------
/** @type {import('../types').Rule.RuleModule} */
module.exports = {
meta: {
type: "suggestion",
hasSuggestions: true,
docs: {
description: "Require the use of `===` and `!==`",
recommended: false,
url: "https://eslint.org/docs/latest/rules/eqeqeq",
},
schema: {
anyOf: [
{
type: "array",
items: [
{
enum: ["always"],
},
{
type: "object",
properties: {
null: {
enum: ["always", "never", "ignore"],
},
},
additionalProperties: false,
},
],
additionalItems: false,
},
{
type: "array",
items: [
{
enum: ["smart", "allow-null"],
},
],
additionalItems: false,
},
],
},
fixable: "code",
messages: {
unexpected:
"Expected '{{expectedOperator}}' and instead saw '{{actualOperator}}'.",
replaceOperator:
"Use '{{expectedOperator}}' instead of '{{actualOperator}}'.",
},
},
create(context) {
const config = context.options[0] || "always";
const options = context.options[1] || {};
const sourceCode = context.sourceCode;
const nullOption =
config === "always" ? options.null || "always" : "ignore";
const enforceRuleForNull = nullOption === "always";
const enforceInverseRuleForNull = nullOption === "never";
/**
* Checks if an expression is a typeof expression
* @param {ASTNode} node The node to check
* @returns {boolean} if the node is a typeof expression
*/
function isTypeOf(node) {
return (
node.type === "UnaryExpression" && node.operator === "typeof"
);
}
/**
* Checks if either operand of a binary expression is a typeof operation
* @param {ASTNode} node The node to check
* @returns {boolean} if one of the operands is typeof
* @private
*/
function isTypeOfBinary(node) {
return isTypeOf(node.left) || isTypeOf(node.right);
}
/**
* Checks if operands are literals of the same type (via typeof)
* @param {ASTNode} node The node to check
* @returns {boolean} if operands are of same type
* @private
*/
function areLiteralsAndSameType(node) {
return (
node.left.type === "Literal" &&
node.right.type === "Literal" &&
typeof node.left.value === typeof node.right.value
);
}
/**
* Checks if one of the operands is a literal null
* @param {ASTNode} node The node to check
* @returns {boolean} if operands are null
* @private
*/
function isNullCheck(node) {
return (
astUtils.isNullLiteral(node.right) ||
astUtils.isNullLiteral(node.left)
);
}
/**
* Reports a message for this rule.
* @param {ASTNode} node The binary expression node that was checked
* @param {string} expectedOperator The operator that was expected (either '==', '!=', '===', or '!==')
* @returns {void}
* @private
*/
function report(node, expectedOperator) {
const operatorToken = sourceCode.getFirstTokenBetween(
node.left,
node.right,
token => token.value === node.operator,
);
const commonReportParams = {
node,
loc: operatorToken.loc,
messageId: "unexpected",
data: { expectedOperator, actualOperator: node.operator },
};
if (isTypeOfBinary(node) || areLiteralsAndSameType(node)) {
context.report({
...commonReportParams,
fix(fixer) {
return fixer.replaceText(
operatorToken,
expectedOperator,
);
},
});
} else {
context.report({
...commonReportParams,
suggest: [
{
messageId: "replaceOperator",
data: {
expectedOperator,
actualOperator: node.operator,
},
fix: fixer =>
fixer.replaceText(
operatorToken,
expectedOperator,
),
},
],
});
}
}
return {
BinaryExpression(node) {
const isNull = isNullCheck(node);
if (node.operator !== "==" && node.operator !== "!=") {
if (enforceInverseRuleForNull && isNull) {
report(node, node.operator.slice(0, -1));
}
return;
}
if (
config === "smart" &&
(isTypeOfBinary(node) ||
areLiteralsAndSameType(node) ||
isNull)
) {
return;
}
if (!enforceRuleForNull && isNull) {
return;
}
report(node, `${node.operator}=`);
},
};
},
};
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