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jsx-curly-brace-presence.js
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jsx-curly-brace-presence.js
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/**
* @fileoverview Enforce curly braces or disallow unnecessary curly brace in JSX
* @author Jacky Ho
* @author Simon Lydell
*/
'use strict';
const docsUrl = require('../util/docsUrl');
const jsxUtil = require('../util/jsx');
// ------------------------------------------------------------------------------
// Constants
// ------------------------------------------------------------------------------
const OPTION_ALWAYS = 'always';
const OPTION_NEVER = 'never';
const OPTION_IGNORE = 'ignore';
const OPTION_VALUES = [
OPTION_ALWAYS,
OPTION_NEVER,
OPTION_IGNORE
];
const DEFAULT_CONFIG = {props: OPTION_NEVER, children: OPTION_NEVER};
// ------------------------------------------------------------------------------
// Rule Definition
// ------------------------------------------------------------------------------
module.exports = {
meta: {
docs: {
description:
'Disallow unnecessary JSX expressions when literals alone are sufficient ' +
'or enfore JSX expressions on literals in JSX children or attributes',
category: 'Stylistic Issues',
recommended: false,
url: docsUrl('jsx-curly-brace-presence')
},
fixable: 'code',
schema: [
{
oneOf: [
{
type: 'object',
properties: {
props: {enum: OPTION_VALUES},
children: {enum: OPTION_VALUES}
},
additionalProperties: false
},
{
enum: OPTION_VALUES
}
]
}
]
},
create: function(context) {
const ruleOptions = context.options[0];
const userConfig = typeof ruleOptions === 'string' ?
{props: ruleOptions, children: ruleOptions} :
Object.assign({}, DEFAULT_CONFIG, ruleOptions);
function containsLineTerminators(rawStringValue) {
return /[\n\r\u2028\u2029]/.test(rawStringValue);
}
function containsBackslash(rawStringValue) {
return rawStringValue.includes('\\');
}
function containsHTMLEntity(rawStringValue) {
return /&[A-Za-z\d#]+;/.test(rawStringValue);
}
function containsDisallowedJSXTextChars(rawStringValue) {
return /[{<>}]/.test(rawStringValue);
}
function containsQuoteCharacters(value) {
return /['"]/.test(value);
}
function escapeDoubleQuotes(rawStringValue) {
return rawStringValue.replace(/\\"/g, '"').replace(/"/g, '\\"');
}
function escapeBackslashes(rawStringValue) {
return rawStringValue.replace(/\\/g, '\\\\');
}
function needToEscapeCharacterForJSX(raw) {
return (
containsBackslash(raw) ||
containsHTMLEntity(raw) ||
containsDisallowedJSXTextChars(raw)
);
}
function containsWhitespaceExpression(child) {
if (child.type === 'JSXExpressionContainer') {
const value = child.expression.value;
return value ? !(/\S/.test(value)) : false;
}
return false;
}
/**
* Report and fix an unnecessary curly brace violation on a node
* @param {ASTNode} JSXExpressionNode - The AST node with an unnecessary JSX expression
*/
function reportUnnecessaryCurly(JSXExpressionNode) {
context.report({
node: JSXExpressionNode,
message: 'Curly braces are unnecessary here.',
fix: function(fixer) {
const expression = JSXExpressionNode.expression;
const expressionType = expression.type;
const parentType = JSXExpressionNode.parent.type;
let textToReplace;
if (parentType === 'JSXAttribute') {
textToReplace = `"${expressionType === 'TemplateLiteral' ?
expression.quasis[0].value.raw :
expression.raw.substring(1, expression.raw.length - 1)
}"`;
} else {
textToReplace = expressionType === 'TemplateLiteral' ?
expression.quasis[0].value.cooked : expression.value;
}
return fixer.replaceText(JSXExpressionNode, textToReplace);
}
});
}
function reportMissingCurly(literalNode) {
context.report({
node: literalNode,
message: 'Need to wrap this literal in a JSX expression.',
fix: function(fixer) {
// If a HTML entity name is found, bail out because it can be fixed
// by either using the real character or the unicode equivalent.
// If it contains any line terminator character, bail out as well.
if (
containsHTMLEntity(literalNode.raw) ||
containsLineTerminators(literalNode.raw)
) {
return null;
}
const expression = literalNode.parent.type === 'JSXAttribute' ?
`{"${escapeDoubleQuotes(escapeBackslashes(
literalNode.raw.substring(1, literalNode.raw.length - 1)
))}"}` :
`{${JSON.stringify(literalNode.value)}}`;
return fixer.replaceText(literalNode, expression);
}
});
}
// Bail out if there is any character that needs to be escaped in JSX
// because escaping decreases readiblity and the original code may be more
// readible anyway or intentional for other specific reasons
function lintUnnecessaryCurly(JSXExpressionNode) {
const expression = JSXExpressionNode.expression;
const expressionType = expression.type;
if (
(expressionType === 'Literal' || expressionType === 'JSXText') &&
typeof expression.value === 'string' &&
!needToEscapeCharacterForJSX(expression.raw) && (
jsxUtil.isJSX(JSXExpressionNode.parent) ||
!containsQuoteCharacters(expression.value)
)
) {
reportUnnecessaryCurly(JSXExpressionNode);
} else if (
expressionType === 'TemplateLiteral' &&
expression.expressions.length === 0 &&
expression.quasis[0].value.raw.indexOf('\n') === -1 &&
!needToEscapeCharacterForJSX(expression.quasis[0].value.raw) && (
jsxUtil.isJSX(JSXExpressionNode.parent) ||
!containsQuoteCharacters(expression.quasis[0].value.cooked)
)
) {
reportUnnecessaryCurly(JSXExpressionNode);
}
}
function areRuleConditionsSatisfied(parent, config, ruleCondition) {
return (
parent.type === 'JSXAttribute' &&
typeof config.props === 'string' &&
config.props === ruleCondition
) || (
jsxUtil.isJSX(parent) &&
typeof config.children === 'string' &&
config.children === ruleCondition
);
}
function shouldCheckForUnnecessaryCurly(parent, config) {
// If there are more than one JSX child, there is no need to check for
// unnecessary curly braces.
if (jsxUtil.isJSX(parent) && parent.children.length !== 1) {
return false;
}
if (
parent.children
&& parent.children.length === 1
&& containsWhitespaceExpression(parent.children[0])
) {
return false;
}
return areRuleConditionsSatisfied(parent, config, OPTION_NEVER);
}
function shouldCheckForMissingCurly(parent, config) {
if (
parent.children
&& parent.children.length === 1
&& containsWhitespaceExpression(parent.children[0])
) {
return false;
}
return areRuleConditionsSatisfied(parent, config, OPTION_ALWAYS);
}
// --------------------------------------------------------------------------
// Public
// --------------------------------------------------------------------------
return {
JSXExpressionContainer: node => {
if (shouldCheckForUnnecessaryCurly(node.parent, userConfig)) {
lintUnnecessaryCurly(node);
}
},
'Literal, JSXText': node => {
if (shouldCheckForMissingCurly(node.parent, userConfig)) {
reportMissingCurly(node);
}
}
};
}
};