/**
* @fileoverview A rule to choose between single and double quote marks
* @author Matt DuVall <http://www.mattduvall.com/>, Brandon Payton
*/
"use strict";
//------------------------------------------------------------------------------
// Requirements
//------------------------------------------------------------------------------
const astUtils = require("../ast-utils");
//------------------------------------------------------------------------------
// Constants
//------------------------------------------------------------------------------
const QUOTE_SETTINGS = {
double: {
quote: "\"",
alternateQuote: "'",
description: "doublequote"
},
single: {
quote: "'",
alternateQuote: "\"",
description: "singlequote"
},
backtick: {
quote: "`",
alternateQuote: "\"",
description: "backtick"
}
};
// An unescaped newline is a newline preceded by an even number of backslashes.
const UNESCAPED_LINEBREAK_PATTERN = new RegExp(String.raw`(^|[^\\])(\\\\)*[${Array.from(astUtils.LINEBREAKS).join("")}]`);
/**
* Switches quoting of javascript string between ' " and `
* escaping and unescaping as necessary.
* Only escaping of the minimal set of characters is changed.
* Note: escaping of newlines when switching from backtick to other quotes is not handled.
* @param {string} str - A string to convert.
* @returns {string} The string with changed quotes.
* @private
*/
QUOTE_SETTINGS.double.convert =
QUOTE_SETTINGS.single.convert =
QUOTE_SETTINGS.backtick.convert = function(str) {
const newQuote = this.quote;
const oldQuote = str[0];
if (newQuote === oldQuote) {
return str;
}
return newQuote + str.slice(1, -1).replace(/\\(\${|\r\n?|\n|.)|["'`]|\${|(\r\n?|\n)/g, (match, escaped, newline) => {
if (escaped === oldQuote || oldQuote === "`" && escaped === "${") {
return escaped; // unescape
}
if (match === newQuote || newQuote === "`" && match === "${") {
return `\\${match}`; // escape
}
if (newline && oldQuote === "`") {
return "\\n"; // escape newlines
}
return match;
}) + newQuote;
};
const AVOID_ESCAPE = "avoid-escape";
//------------------------------------------------------------------------------
// Rule Definition
//------------------------------------------------------------------------------
module.exports = {
meta: {
docs: {
description: "enforce the consistent use of either backticks, double, or single quotes",
category: "Stylistic Issues",
recommended: false,
url: "https://eslint.org/docs/rules/quotes"
},
fixable: "code",
schema: [
{
enum: ["single", "double", "backtick"]
},
{
anyOf: [
{
enum: ["avoid-escape"]
},
{
type: "object",
properties: {
avoidEscape: {
type: "boolean"
},
allowTemplateLiterals: {
type: "boolean"
}
},
additionalProperties: false
}
]
}
]
},
create(context) {
const quoteOption = context.options[0],
settings = QUOTE_SETTINGS[quoteOption || "double"],
options = context.options[1],
allowTemplateLiterals = options && options.allowTemplateLiterals === true,
sourceCode = context.getSourceCode();
let avoidEscape = options && options.avoidEscape === true;
// deprecated
if (options === AVOID_ESCAPE) {
avoidEscape = true;
}
/**
* Determines if a given node is part of JSX syntax.
*
* This function returns `true` in the following cases:
*
* - `<div className="foo"></div>` ... If the literal is an attribute value, the parent of the literal is `JSXAttribute`.
* - `<div>foo</div>` ... If the literal is a text content, the parent of the literal is `JSXElement`.
*
* In particular, this function returns `false` in the following cases:
*
* - `<div className={"foo"}></div>`
* - `<div>{"foo"}</div>`
*
* In both cases, inside of the braces is handled as normal JavaScript.
* The braces are `JSXExpressionContainer` nodes.
*
* @param {ASTNode} node The Literal node to check.
* @returns {boolean} True if the node is a part of JSX, false if not.
* @private
*/
function isJSXLiteral(node) {
return node.parent.type === "JSXAttribute" || node.parent.type === "JSXElement";
}
/**
* Checks whether or not a given node is a directive.
* The directive is a `ExpressionStatement` which has only a string literal.
* @param {ASTNode} node - A node to check.
* @returns {boolean} Whether or not the node is a directive.
* @private
*/
function isDirective(node) {
return (
node.type === "ExpressionStatement" &&
node.expression.type === "Literal" &&
typeof node.expression.value === "string"
);
}
/**
* Checks whether or not a given node is a part of directive prologues.
* See also: http://www.ecma-international.org/ecma-262/6.0/#sec-directive-prologues-and-the-use-strict-directive
* @param {ASTNode} node - A node to check.
* @returns {boolean} Whether or not the node is a part of directive prologues.
* @private
*/
function isPartOfDirectivePrologue(node) {
const block = node.parent.parent;
if (block.type !== "Program" && (block.type !== "BlockStatement" || !astUtils.isFunction(block.parent))) {
return false;
}
// Check the node is at a prologue.
for (let i = 0; i < block.body.length; ++i) {
const statement = block.body[i];
if (statement === node.parent) {
return true;
}
if (!isDirective(statement)) {
break;
}
}
return false;
}
/**
* Checks whether or not a given node is allowed as non backtick.
* @param {ASTNode} node - A node to check.
* @returns {boolean} Whether or not the node is allowed as non backtick.
* @private
*/
function isAllowedAsNonBacktick(node) {
const parent = node.parent;
switch (parent.type) {
// Directive Prologues.
case "ExpressionStatement":
return isPartOfDirectivePrologue(node);
// LiteralPropertyName.
case "Property":
case "MethodDefinition":
return parent.key === node && !parent.computed;
// ModuleSpecifier.
case "ImportDeclaration":
case "ExportNamedDeclaration":
case "ExportAllDeclaration":
return parent.source === node;
// Others don't allow.
default:
return false;
}
}
return {
Literal(node) {
const val = node.value,
rawVal = node.raw;
if (settings && typeof val === "string") {
let isValid = (quoteOption === "backtick" && isAllowedAsNonBacktick(node)) ||
isJSXLiteral(node) ||
astUtils.isSurroundedBy(rawVal, settings.quote);
if (!isValid && avoidEscape) {
isValid = astUtils.isSurroundedBy(rawVal, settings.alternateQuote) && rawVal.indexOf(settings.quote) >= 0;
}
if (!isValid) {
context.report({
node,
message: "Strings must use {{description}}.",
data: {
description: settings.description
},
fix(fixer) {
return fixer.replaceText(node, settings.convert(node.raw));
}
});
}
}
},
TemplateLiteral(node) {
// If backticks are expected or it's a tagged template, then this shouldn't throw an errors
if (
allowTemplateLiterals ||
quoteOption === "backtick" ||
node.parent.type === "TaggedTemplateExpression" && node === node.parent.quasi
) {
return;
}
// A warning should be produced if the template literal only has one TemplateElement, and has no unescaped newlines.
const shouldWarn = node.quasis.length === 1 && !UNESCAPED_LINEBREAK_PATTERN.test(node.quasis[0].value.raw);
if (shouldWarn) {
context.report({
node,
message: "Strings must use {{description}}.",
data: {
description: settings.description
},
fix(fixer) {
if (isPartOfDirectivePrologue(node)) {
/*
* TemplateLiterals in a directive prologue aren't actually directives, but if they're
* in the directive prologue, then fixing them might turn them into directives and change
* the behavior of the code.
*/
return null;
}
return fixer.replaceText(node, settings.convert(sourceCode.getText(node)));
}
});
}
}
};
}
};