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/**
* @fileoverview Prefer boolean length check
*
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/.
*/
"use strict";
function funcForBooleanLength(context, node, conditionCheck) {
let newText = "";
const sourceCode = context.getSourceCode();
switch (node.operator) {
case ">":
if (node.right.value == 0) {
if (conditionCheck) {
newText = sourceCode.getText(node.left);
} else {
newText = "!!" + sourceCode.getText(node.left);
}
} else {
newText = "!" + sourceCode.getText(node.right);
}
break;
case "<":
if (node.right.value == 0) {
newText = "!" + sourceCode.getText(node.left);
} else if (conditionCheck) {
newText = sourceCode.getText(node.right);
} else {
newText = "!!" + sourceCode.getText(node.right);
}
break;
case "==":
if (node.right.value == 0) {
newText = "!" + sourceCode.getText(node.left);
} else {
newText = "!" + sourceCode.getText(node.right);
}
break;
case "!=":
if (node.right.value == 0) {
if (conditionCheck) {
newText = sourceCode.getText(node.left);
} else {
newText = "!!" + sourceCode.getText(node.left);
}
} else if (conditionCheck) {
newText = sourceCode.getText(node.right);
} else {
newText = "!!" + sourceCode.getText(node.right);
}
break;
}
return newText;
}
module.exports = {
meta: {
docs: {
url: "https://firefox-source-docs.mozilla.org/code-quality/lint/linters/eslint-plugin-mozilla/prefer-boolean-length-check.html",
},
fixable: "code",
messages: {
preferBooleanCheck: "Prefer boolean length check",
},
schema: [],
type: "suggestion",
},
create(context) {
const conditionStatement = [
"IfStatement",
"WhileStatement",
"DoWhileStatement",
"ForStatement",
"ForInStatement",
"ConditionalExpression",
];
return {
BinaryExpression(node) {
if (
["==", "!=", ">", "<"].includes(node.operator) &&
((node.right.type == "Literal" &&
node.right.value == 0 &&
node.left.property?.name == "length") ||
(node.left.type == "Literal" &&
node.left.value == 0 &&
node.right.property?.name == "length"))
) {
if (
conditionStatement.includes(node.parent.type) ||
(node.parent.type == "LogicalExpression" &&
conditionStatement.includes(node.parent.parent.type))
) {
context.report({
node,
fix: fixer => {
let generateExpression = funcForBooleanLength(
context,
node,
true
);
return fixer.replaceText(node, generateExpression);
},
messageId: "preferBooleanCheck",
});
} else {
context.report({
node,
fix: fixer => {
let generateExpression = funcForBooleanLength(
context,
node,
false
);
return fixer.replaceText(node, generateExpression);
},
messageId: "preferBooleanCheck",
});
}
}
},
};
},
};
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