no-base-to-string.js
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"use strict";
var __createBinding = (this && this.__createBinding) || (Object.create ? (function(o, m, k, k2) {
if (k2 === undefined) k2 = k;
Object.defineProperty(o, k2, { enumerable: true, get: function() { return m[k]; } });
}) : (function(o, m, k, k2) {
if (k2 === undefined) k2 = k;
o[k2] = m[k];
}));
var __setModuleDefault = (this && this.__setModuleDefault) || (Object.create ? (function(o, v) {
Object.defineProperty(o, "default", { enumerable: true, value: v });
}) : function(o, v) {
o["default"] = v;
});
var __importStar = (this && this.__importStar) || function (mod) {
if (mod && mod.__esModule) return mod;
var result = {};
if (mod != null) for (var k in mod) if (k !== "default" && Object.prototype.hasOwnProperty.call(mod, k)) __createBinding(result, mod, k);
__setModuleDefault(result, mod);
return result;
};
Object.defineProperty(exports, "__esModule", { value: true });
const experimental_utils_1 = require("@typescript-eslint/experimental-utils");
const ts = __importStar(require("typescript"));
const util = __importStar(require("../util"));
var Usefulness;
(function (Usefulness) {
Usefulness[Usefulness["Always"] = 0] = "Always";
Usefulness["Never"] = "will";
Usefulness["Sometimes"] = "may";
})(Usefulness || (Usefulness = {}));
exports.default = util.createRule({
name: 'no-base-to-string',
meta: {
docs: {
description: 'Requires that `.toString()` is only called on objects which provide useful information when stringified',
category: 'Best Practices',
recommended: false,
requiresTypeChecking: true,
},
messages: {
baseToString: "'{{name}} {{certainty}} evaluate to '[object Object]' when stringified.",
},
schema: [
{
type: 'object',
properties: {
ignoredTypeNames: {
type: 'array',
items: {
type: 'string',
},
},
},
additionalProperties: false,
},
],
type: 'suggestion',
},
defaultOptions: [
{
ignoredTypeNames: ['RegExp'],
},
],
create(context, [option]) {
var _a;
const parserServices = util.getParserServices(context);
const typeChecker = parserServices.program.getTypeChecker();
const ignoredTypeNames = (_a = option.ignoredTypeNames) !== null && _a !== void 0 ? _a : [];
function checkExpression(node, type) {
if (node.type === experimental_utils_1.AST_NODE_TYPES.Literal) {
return;
}
const certainty = collectToStringCertainty(type !== null && type !== void 0 ? type : typeChecker.getTypeAtLocation(parserServices.esTreeNodeToTSNodeMap.get(node)));
if (certainty === Usefulness.Always) {
return;
}
context.report({
data: {
certainty,
name: context.getSourceCode().getText(node),
},
messageId: 'baseToString',
node,
});
}
function collectToStringCertainty(type) {
const toString = typeChecker.getPropertyOfType(type, 'toString');
const declarations = toString === null || toString === void 0 ? void 0 : toString.getDeclarations();
if (!toString || !declarations || declarations.length === 0) {
return Usefulness.Always;
}
// Patch for old version TypeScript, the Boolean type definition missing toString()
if (type.flags & ts.TypeFlags.Boolean ||
type.flags & ts.TypeFlags.BooleanLiteral) {
return Usefulness.Always;
}
if (ignoredTypeNames.includes(util.getTypeName(typeChecker, type))) {
return Usefulness.Always;
}
if (declarations.every(({ parent }) => !ts.isInterfaceDeclaration(parent) || parent.name.text !== 'Object')) {
return Usefulness.Always;
}
if (type.isIntersection()) {
for (const subType of type.types) {
const subtypeUsefulness = collectToStringCertainty(subType);
if (subtypeUsefulness === Usefulness.Always) {
return Usefulness.Always;
}
}
return Usefulness.Never;
}
if (!type.isUnion()) {
return Usefulness.Never;
}
let allSubtypesUseful = true;
let someSubtypeUseful = false;
for (const subType of type.types) {
const subtypeUsefulness = collectToStringCertainty(subType);
if (subtypeUsefulness !== Usefulness.Always && allSubtypesUseful) {
allSubtypesUseful = false;
}
if (subtypeUsefulness !== Usefulness.Never && !someSubtypeUseful) {
someSubtypeUseful = true;
}
}
if (allSubtypesUseful && someSubtypeUseful) {
return Usefulness.Always;
}
if (someSubtypeUseful) {
return Usefulness.Sometimes;
}
return Usefulness.Never;
}
return {
'AssignmentExpression[operator = "+="], BinaryExpression[operator = "+"]'(node) {
const leftType = typeChecker.getTypeAtLocation(parserServices.esTreeNodeToTSNodeMap.get(node.left));
const rightType = typeChecker.getTypeAtLocation(parserServices.esTreeNodeToTSNodeMap.get(node.right));
if (util.getTypeName(typeChecker, leftType) === 'string') {
checkExpression(node.right, rightType);
}
else if (util.getTypeName(typeChecker, rightType) === 'string') {
checkExpression(node.left, leftType);
}
},
'CallExpression > MemberExpression.callee > Identifier[name = "toString"].property'(node) {
const memberExpr = node.parent;
checkExpression(memberExpr.object);
},
TemplateLiteral(node) {
if (node.parent &&
node.parent.type === experimental_utils_1.AST_NODE_TYPES.TaggedTemplateExpression) {
return;
}
for (const expression of node.expressions) {
checkExpression(expression);
}
},
};
},
});
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