Current File : /var/www/html/node_modules/eslint/lib/rules/object-shorthand.js
/**
* @fileoverview Rule to enforce concise object methods and properties.
* @author Jamund Ferguson
*/
"use strict";
const OPTIONS = {
always: "always",
never: "never",
methods: "methods",
properties: "properties",
consistent: "consistent",
consistentAsNeeded: "consistent-as-needed"
};
//------------------------------------------------------------------------------
// Requirements
//------------------------------------------------------------------------------
const astUtils = require("./utils/ast-utils");
//------------------------------------------------------------------------------
// Rule Definition
//------------------------------------------------------------------------------
/** @type {import('../shared/types').Rule} */
module.exports = {
meta: {
type: "suggestion",
docs: {
description: "require or disallow method and property shorthand syntax for object literals",
recommended: false,
url: "https://eslint.org/docs/rules/object-shorthand"
},
fixable: "code",
schema: {
anyOf: [
{
type: "array",
items: [
{
enum: ["always", "methods", "properties", "never", "consistent", "consistent-as-needed"]
}
],
minItems: 0,
maxItems: 1
},
{
type: "array",
items: [
{
enum: ["always", "methods", "properties"]
},
{
type: "object",
properties: {
avoidQuotes: {
type: "boolean"
}
},
additionalProperties: false
}
],
minItems: 0,
maxItems: 2
},
{
type: "array",
items: [
{
enum: ["always", "methods"]
},
{
type: "object",
properties: {
ignoreConstructors: {
type: "boolean"
},
avoidQuotes: {
type: "boolean"
},
avoidExplicitReturnArrows: {
type: "boolean"
}
},
additionalProperties: false
}
],
minItems: 0,
maxItems: 2
}
]
},
messages: {
expectedAllPropertiesShorthanded: "Expected shorthand for all properties.",
expectedLiteralMethodLongform: "Expected longform method syntax for string literal keys.",
expectedPropertyShorthand: "Expected property shorthand.",
expectedPropertyLongform: "Expected longform property syntax.",
expectedMethodShorthand: "Expected method shorthand.",
expectedMethodLongform: "Expected longform method syntax.",
unexpectedMix: "Unexpected mix of shorthand and non-shorthand properties."
}
},
create(context) {
const APPLY = context.options[0] || OPTIONS.always;
const APPLY_TO_METHODS = APPLY === OPTIONS.methods || APPLY === OPTIONS.always;
const APPLY_TO_PROPS = APPLY === OPTIONS.properties || APPLY === OPTIONS.always;
const APPLY_NEVER = APPLY === OPTIONS.never;
const APPLY_CONSISTENT = APPLY === OPTIONS.consistent;
const APPLY_CONSISTENT_AS_NEEDED = APPLY === OPTIONS.consistentAsNeeded;
const PARAMS = context.options[1] || {};
const IGNORE_CONSTRUCTORS = PARAMS.ignoreConstructors;
const AVOID_QUOTES = PARAMS.avoidQuotes;
const AVOID_EXPLICIT_RETURN_ARROWS = !!PARAMS.avoidExplicitReturnArrows;
const sourceCode = context.getSourceCode();
//--------------------------------------------------------------------------
// Helpers
//--------------------------------------------------------------------------
const CTOR_PREFIX_REGEX = /[^_$0-9]/u;
/**
* Determines if the first character of the name is a capital letter.
* @param {string} name The name of the node to evaluate.
* @returns {boolean} True if the first character of the property name is a capital letter, false if not.
* @private
*/
function isConstructor(name) {
const match = CTOR_PREFIX_REGEX.exec(name);
// Not a constructor if name has no characters apart from '_', '$' and digits e.g. '_', '$$', '_8'
if (!match) {
return false;
}
const firstChar = name.charAt(match.index);
return firstChar === firstChar.toUpperCase();
}
/**
* Determines if the property can have a shorthand form.
* @param {ASTNode} property Property AST node
* @returns {boolean} True if the property can have a shorthand form
* @private
*/
function canHaveShorthand(property) {
return (property.kind !== "set" && property.kind !== "get" && property.type !== "SpreadElement" && property.type !== "SpreadProperty" && property.type !== "ExperimentalSpreadProperty");
}
/**
* Checks whether a node is a string literal.
* @param {ASTNode} node Any AST node.
* @returns {boolean} `true` if it is a string literal.
*/
function isStringLiteral(node) {
return node.type === "Literal" && typeof node.value === "string";
}
/**
* Determines if the property is a shorthand or not.
* @param {ASTNode} property Property AST node
* @returns {boolean} True if the property is considered shorthand, false if not.
* @private
*/
function isShorthand(property) {
// property.method is true when `{a(){}}`.
return (property.shorthand || property.method);
}
/**
* Determines if the property's key and method or value are named equally.
* @param {ASTNode} property Property AST node
* @returns {boolean} True if the key and value are named equally, false if not.
* @private
*/
function isRedundant(property) {
const value = property.value;
if (value.type === "FunctionExpression") {
return !value.id; // Only anonymous should be shorthand method.
}
if (value.type === "Identifier") {
return astUtils.getStaticPropertyName(property) === value.name;
}
return false;
}
/**
* Ensures that an object's properties are consistently shorthand, or not shorthand at all.
* @param {ASTNode} node Property AST node
* @param {boolean} checkRedundancy Whether to check longform redundancy
* @returns {void}
*/
function checkConsistency(node, checkRedundancy) {
// We are excluding getters/setters and spread properties as they are considered neither longform nor shorthand.
const properties = node.properties.filter(canHaveShorthand);
// Do we still have properties left after filtering the getters and setters?
if (properties.length > 0) {
const shorthandProperties = properties.filter(isShorthand);
/*
* If we do not have an equal number of longform properties as
* shorthand properties, we are using the annotations inconsistently
*/
if (shorthandProperties.length !== properties.length) {
// We have at least 1 shorthand property
if (shorthandProperties.length > 0) {
context.report({ node, messageId: "unexpectedMix" });
} else if (checkRedundancy) {
/*
* If all properties of the object contain a method or value with a name matching it's key,
* all the keys are redundant.
*/
const canAlwaysUseShorthand = properties.every(isRedundant);
if (canAlwaysUseShorthand) {
context.report({ node, messageId: "expectedAllPropertiesShorthanded" });
}
}
}
}
}
/**
* Fixes a FunctionExpression node by making it into a shorthand property.
* @param {SourceCodeFixer} fixer The fixer object
* @param {ASTNode} node A `Property` node that has a `FunctionExpression` or `ArrowFunctionExpression` as its value
* @returns {Object} A fix for this node
*/
function makeFunctionShorthand(fixer, node) {
const firstKeyToken = node.computed
? sourceCode.getFirstToken(node, astUtils.isOpeningBracketToken)
: sourceCode.getFirstToken(node.key);
const lastKeyToken = node.computed
? sourceCode.getFirstTokenBetween(node.key, node.value, astUtils.isClosingBracketToken)
: sourceCode.getLastToken(node.key);
const keyText = sourceCode.text.slice(firstKeyToken.range[0], lastKeyToken.range[1]);
let keyPrefix = "";
// key: /* */ () => {}
if (sourceCode.commentsExistBetween(lastKeyToken, node.value)) {
return null;
}
if (node.value.async) {
keyPrefix += "async ";
}
if (node.value.generator) {
keyPrefix += "*";
}
const fixRange = [firstKeyToken.range[0], node.range[1]];
const methodPrefix = keyPrefix + keyText;
if (node.value.type === "FunctionExpression") {
const functionToken = sourceCode.getTokens(node.value).find(token => token.type === "Keyword" && token.value === "function");
const tokenBeforeParams = node.value.generator ? sourceCode.getTokenAfter(functionToken) : functionToken;
return fixer.replaceTextRange(
fixRange,
methodPrefix + sourceCode.text.slice(tokenBeforeParams.range[1], node.value.range[1])
);
}
const arrowToken = sourceCode.getTokenBefore(node.value.body, astUtils.isArrowToken);
const fnBody = sourceCode.text.slice(arrowToken.range[1], node.value.range[1]);
let shouldAddParensAroundParameters = false;
let tokenBeforeParams;
if (node.value.params.length === 0) {
tokenBeforeParams = sourceCode.getFirstToken(node.value, astUtils.isOpeningParenToken);
} else {
tokenBeforeParams = sourceCode.getTokenBefore(node.value.params[0]);
}
if (node.value.params.length === 1) {
const hasParen = astUtils.isOpeningParenToken(tokenBeforeParams);
const isTokenOutsideNode = tokenBeforeParams.range[0] < node.range[0];
shouldAddParensAroundParameters = !hasParen || isTokenOutsideNode;
}
const sliceStart = shouldAddParensAroundParameters
? node.value.params[0].range[0]
: tokenBeforeParams.range[0];
const sliceEnd = sourceCode.getTokenBefore(arrowToken).range[1];
const oldParamText = sourceCode.text.slice(sliceStart, sliceEnd);
const newParamText = shouldAddParensAroundParameters ? `(${oldParamText})` : oldParamText;
return fixer.replaceTextRange(
fixRange,
methodPrefix + newParamText + fnBody
);
}
/**
* Fixes a FunctionExpression node by making it into a longform property.
* @param {SourceCodeFixer} fixer The fixer object
* @param {ASTNode} node A `Property` node that has a `FunctionExpression` as its value
* @returns {Object} A fix for this node
*/
function makeFunctionLongform(fixer, node) {
const firstKeyToken = node.computed ? sourceCode.getTokens(node).find(token => token.value === "[") : sourceCode.getFirstToken(node.key);
const lastKeyToken = node.computed ? sourceCode.getTokensBetween(node.key, node.value).find(token => token.value === "]") : sourceCode.getLastToken(node.key);
const keyText = sourceCode.text.slice(firstKeyToken.range[0], lastKeyToken.range[1]);
let functionHeader = "function";
if (node.value.async) {
functionHeader = `async ${functionHeader}`;
}
if (node.value.generator) {
functionHeader = `${functionHeader}*`;
}
return fixer.replaceTextRange([node.range[0], lastKeyToken.range[1]], `${keyText}: ${functionHeader}`);
}
/*
* To determine whether a given arrow function has a lexical identifier (`this`, `arguments`, `super`, or `new.target`),
* create a stack of functions that define these identifiers (i.e. all functions except arrow functions) as the AST is
* traversed. Whenever a new function is encountered, create a new entry on the stack (corresponding to a different lexical
* scope of `this`), and whenever a function is exited, pop that entry off the stack. When an arrow function is entered,
* keep a reference to it on the current stack entry, and remove that reference when the arrow function is exited.
* When a lexical identifier is encountered, mark all the arrow functions on the current stack entry by adding them
* to an `arrowsWithLexicalIdentifiers` set. Any arrow function in that set will not be reported by this rule,
* because converting it into a method would change the value of one of the lexical identifiers.
*/
const lexicalScopeStack = [];
const arrowsWithLexicalIdentifiers = new WeakSet();
const argumentsIdentifiers = new WeakSet();
/**
* Enters a function. This creates a new lexical identifier scope, so a new Set of arrow functions is pushed onto the stack.
* Also, this marks all `arguments` identifiers so that they can be detected later.
* @returns {void}
*/
function enterFunction() {
lexicalScopeStack.unshift(new Set());
context.getScope().variables.filter(variable => variable.name === "arguments").forEach(variable => {
variable.references.map(ref => ref.identifier).forEach(identifier => argumentsIdentifiers.add(identifier));
});
}
/**
* Exits a function. This pops the current set of arrow functions off the lexical scope stack.
* @returns {void}
*/
function exitFunction() {
lexicalScopeStack.shift();
}
/**
* Marks the current function as having a lexical keyword. This implies that all arrow functions
* in the current lexical scope contain a reference to this lexical keyword.
* @returns {void}
*/
function reportLexicalIdentifier() {
lexicalScopeStack[0].forEach(arrowFunction => arrowsWithLexicalIdentifiers.add(arrowFunction));
}
//--------------------------------------------------------------------------
// Public
//--------------------------------------------------------------------------
return {
Program: enterFunction,
FunctionDeclaration: enterFunction,
FunctionExpression: enterFunction,
"Program:exit": exitFunction,
"FunctionDeclaration:exit": exitFunction,
"FunctionExpression:exit": exitFunction,
ArrowFunctionExpression(node) {
lexicalScopeStack[0].add(node);
},
"ArrowFunctionExpression:exit"(node) {
lexicalScopeStack[0].delete(node);
},
ThisExpression: reportLexicalIdentifier,
Super: reportLexicalIdentifier,
MetaProperty(node) {
if (node.meta.name === "new" && node.property.name === "target") {
reportLexicalIdentifier();
}
},
Identifier(node) {
if (argumentsIdentifiers.has(node)) {
reportLexicalIdentifier();
}
},
ObjectExpression(node) {
if (APPLY_CONSISTENT) {
checkConsistency(node, false);
} else if (APPLY_CONSISTENT_AS_NEEDED) {
checkConsistency(node, true);
}
},
"Property:exit"(node) {
const isConciseProperty = node.method || node.shorthand;
// Ignore destructuring assignment
if (node.parent.type === "ObjectPattern") {
return;
}
// getters and setters are ignored
if (node.kind === "get" || node.kind === "set") {
return;
}
// only computed methods can fail the following checks
if (node.computed && node.value.type !== "FunctionExpression" && node.value.type !== "ArrowFunctionExpression") {
return;
}
//--------------------------------------------------------------
// Checks for property/method shorthand.
if (isConciseProperty) {
if (node.method && (APPLY_NEVER || AVOID_QUOTES && isStringLiteral(node.key))) {
const messageId = APPLY_NEVER ? "expectedMethodLongform" : "expectedLiteralMethodLongform";
// { x() {} } should be written as { x: function() {} }
context.report({
node,
messageId,
fix: fixer => makeFunctionLongform(fixer, node)
});
} else if (APPLY_NEVER) {
// { x } should be written as { x: x }
context.report({
node,
messageId: "expectedPropertyLongform",
fix: fixer => fixer.insertTextAfter(node.key, `: ${node.key.name}`)
});
}
} else if (APPLY_TO_METHODS && !node.value.id && (node.value.type === "FunctionExpression" || node.value.type === "ArrowFunctionExpression")) {
if (IGNORE_CONSTRUCTORS && node.key.type === "Identifier" && isConstructor(node.key.name)) {
return;
}
if (AVOID_QUOTES && isStringLiteral(node.key)) {
return;
}
// {[x]: function(){}} should be written as {[x]() {}}
if (node.value.type === "FunctionExpression" ||
node.value.type === "ArrowFunctionExpression" &&
node.value.body.type === "BlockStatement" &&
AVOID_EXPLICIT_RETURN_ARROWS &&
!arrowsWithLexicalIdentifiers.has(node.value)
) {
context.report({
node,
messageId: "expectedMethodShorthand",
fix: fixer => makeFunctionShorthand(fixer, node)
});
}
} else if (node.value.type === "Identifier" && node.key.name === node.value.name && APPLY_TO_PROPS) {
// {x: x} should be written as {x}
context.report({
node,
messageId: "expectedPropertyShorthand",
fix(fixer) {
return fixer.replaceText(node, node.value.name);
}
});
} else if (node.value.type === "Identifier" && node.key.type === "Literal" && node.key.value === node.value.name && APPLY_TO_PROPS) {
if (AVOID_QUOTES) {
return;
}
// {"x": x} should be written as {x}
context.report({
node,
messageId: "expectedPropertyShorthand",
fix(fixer) {
return fixer.replaceText(node, node.value.name);
}
});
}
}
};
}
};
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