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/**
* @fileoverview Rule to warn about using dot notation instead of square bracket notation when possible.
* @author Josh Perez
*/
"use strict";
//------------------------------------------------------------------------------
// Requirements
//------------------------------------------------------------------------------
const astUtils = require("../util/ast-utils");
//------------------------------------------------------------------------------
// Rule Definition
//------------------------------------------------------------------------------
const validIdentifier = /^[a-zA-Z_$][a-zA-Z0-9_$]*$/;
const keywords = require("../util/keywords");
module.exports = {
meta: {
type: "suggestion",
docs: {
description: "enforce dot notation whenever possible",
category: "Best Practices",
recommended: false,
url: "https://eslint.org/docs/rules/dot-notation"
},
schema: [
{
type: "object",
properties: {
allowKeywords: {
type: "boolean",
default: true
},
allowPattern: {
type: "string",
default: ""
}
},
additionalProperties: false
}
],
fixable: "code",
messages: {
useDot: "[{{key}}] is better written in dot notation.",
useBrackets: ".{{key}} is a syntax error."
}
},
create(context) {
const options = context.options[0] || {};
const allowKeywords = options.allowKeywords === void 0 || options.allowKeywords;
const sourceCode = context.getSourceCode();
let allowPattern;
if (options.allowPattern) {
allowPattern = new RegExp(options.allowPattern);
}
/**
* Check if the property is valid dot notation
* @param {ASTNode} node The dot notation node
* @param {string} value Value which is to be checked
* @returns {void}
*/
function checkComputedProperty(node, value) {
if (
validIdentifier.test(value) &&
(allowKeywords || keywords.indexOf(String(value)) === -1) &&
!(allowPattern && allowPattern.test(value))
) {
const formattedValue = node.property.type === "Literal" ? JSON.stringify(value) : `\`${value}\``;
context.report({
node: node.property,
messageId: "useDot",
data: {
key: formattedValue
},
fix(fixer) {
const leftBracket = sourceCode.getTokenAfter(node.object, astUtils.isOpeningBracketToken);
const rightBracket = sourceCode.getLastToken(node);
if (sourceCode.getFirstTokenBetween(leftBracket, rightBracket, { includeComments: true, filter: astUtils.isCommentToken })) {
// Don't perform any fixes if there are comments inside the brackets.
return null;
}
const tokenAfterProperty = sourceCode.getTokenAfter(rightBracket);
const needsSpaceAfterProperty = tokenAfterProperty &&
rightBracket.range[1] === tokenAfterProperty.range[0] &&
!astUtils.canTokensBeAdjacent(String(value), tokenAfterProperty);
const textBeforeDot = astUtils.isDecimalInteger(node.object) ? " " : "";
const textAfterProperty = needsSpaceAfterProperty ? " " : "";
return fixer.replaceTextRange(
[leftBracket.range[0], rightBracket.range[1]],
`${textBeforeDot}.${value}${textAfterProperty}`
);
}
});
}
}
return {
MemberExpression(node) {
if (
node.computed &&
node.property.type === "Literal"
) {
checkComputedProperty(node, node.property.value);
}
if (
node.computed &&
node.property.type === "TemplateLiteral" &&
node.property.expressions.length === 0
) {
checkComputedProperty(node, node.property.quasis[0].value.cooked);
}
if (
!allowKeywords &&
!node.computed &&
keywords.indexOf(String(node.property.name)) !== -1
) {
context.report({
node: node.property,
messageId: "useBrackets",
data: {
key: node.property.name
},
fix(fixer) {
const dot = sourceCode.getTokenBefore(node.property);
const textAfterDot = sourceCode.text.slice(dot.range[1], node.property.range[0]);
if (textAfterDot.trim()) {
// Don't perform any fixes if there are comments between the dot and the property name.
return null;
}
if (node.object.type === "Identifier" && node.object.name === "let") {
/*
* A statement that starts with `let[` is parsed as a destructuring variable declaration, not
* a MemberExpression.
*/
return null;
}
return fixer.replaceTextRange(
[dot.range[0], node.property.range[1]],
`[${textAfterDot}"${node.property.name}"]`
);
}
});
}
}
};
}
};
|
