webpack/lib/errors/JSONParseError.js

Packs ECMAScript/CommonJs/AMD modules for the browser. Allows you to split your codebase into multiple bundles, which can be loaded on demand. Supports loaders to preprocess files, i.e. json, jsx, es7, css, less, ... and your custom stuff.

/*
	MIT License http://www.opensource.org/licenses/mit-license.php
*/

"use strict";

/** @typedef {import("../serialization/ObjectMiddleware").ObjectDeserializerContext} ObjectDeserializerContext */
/** @typedef {import("../serialization/ObjectMiddleware").ObjectSerializerContext} ObjectSerializerContext */

const makeSerializable = require("../util/makeSerializable");

const CONTEXT = 20;

class JSONParseError extends SyntaxError {
	/**
	 * @param {Error} err err
	 * @param {EXPECTED_ANY} raw raw
	 * @param {string} txt text
	 */
	constructor(err, raw, txt) {
		let originalMessage = err.message;
		/** @type {string} */
		let message;
		/** @type {number} */
		let position;

		if (typeof raw !== "string") {
			message = `Cannot parse ${Array.isArray(raw) && raw.length === 0 ? "an empty array" : String(raw)}`;
			position = 0;
		} else if (!txt) {
			message = `${originalMessage} while parsing empty string`;
			position = 0;
		} else {
			// Node 20 puts single quotes around the token and a comma after it
			const UNEXPECTED_TOKEN = /^Unexpected token '?(.)'?(,)? /i;
			const badTokenMatch = originalMessage.match(UNEXPECTED_TOKEN);
			const badIndexMatch = originalMessage.match(/ position\s+(\d+)/i);

			if (badTokenMatch) {
				const h = badTokenMatch[1].charCodeAt(0).toString(16).toUpperCase();
				const hex = `0x${h.length % 2 ? "0" : ""}${h}`;

				originalMessage = originalMessage.replace(
					UNEXPECTED_TOKEN,
					`Unexpected token ${JSON.stringify(badTokenMatch[1])} (${hex})$2 `
				);
			}

			/** @type {number | undefined} */
			let errIdx;

			if (badIndexMatch) {
				errIdx = Number(badIndexMatch[1]);
			} else if (
				// doesn't happen in Node 22+
				/^Unexpected end of JSON.*/i.test(originalMessage)
			) {
				errIdx = txt.length - 1;
			}

			if (errIdx === undefined) {
				message = `${originalMessage} while parsing '${txt.slice(0, CONTEXT * 2)}'`;
				position = 0;
			} else {
				const start = errIdx <= CONTEXT ? 0 : errIdx - CONTEXT;
				const end =
					errIdx + CONTEXT >= txt.length ? txt.length : errIdx + CONTEXT;
				const slice = `${start ? "..." : ""}${txt.slice(start, end)}${end === txt.length ? "" : "..."}`;

				message = `${originalMessage} while parsing ${txt === slice ? "" : "near "}${JSON.stringify(slice)}`;
				position = errIdx;
			}
		}

		super(message);

		/** @type {string} */
		this.name = "JSONParseError";
		/** @type {string | undefined} */
		this.stack = undefined;
		/** @type {Error} */
		this.systemError = err;
		/** @type {EXPECTED_ANY} */
		this.raw = raw;
		/** @type {string} */
		this.txt = txt;
		/** @type {number} */
		this.position = position;
	}

	/**
	 * Serializes this instance into the provided serializer context.
	 * @param {ObjectSerializerContext} context context
	 */
	serialize({ write }) {
		write(this.systemError);
		write(this.raw);
		write(this.txt);
	}

	/**
	 * Restores this instance from the provided deserializer context.
	 * @param {ObjectDeserializerContext} context context
	 * @returns {JSONParseError} DelegatedModule
	 */
	static deserialize(context) {
		const { read } = context;
		return new JSONParseError(read(), read(), read());
	}
}

makeSerializable(JSONParseError, "webpack/lib/errors/JSONParseError");

module.exports = JSONParseError;