strip-json-comments.js
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/*
MIT License http://www.opensource.org/licenses/mit-license.php
Author Natsu @xiaoxiaojx
This file contains code ported from strip-json-comments:
https://github.com/sindresorhus/strip-json-comments
Original license: MIT
Original author: Sindre Sorhus
*/
"use strict";
/**
* @typedef {object} StripJsonCommentsOptions
* @property {boolean=} whitespace Replace comments with whitespace
* @property {boolean=} trailingCommas Strip trailing commas
*/
const singleComment = Symbol("singleComment");
const multiComment = Symbol("multiComment");
/**
* Strip without whitespace (returns empty string)
* @param {string} _string Unused
* @param {number} _start Unused
* @param {number} _end Unused
* @returns {string} Empty string for all input
*/
const stripWithoutWhitespace = (_string, _start, _end) => "";
/**
* Replace all characters except ASCII spaces, tabs and line endings with regular spaces to ensure valid JSON output.
* @param {string} string String to process
* @param {number} start Start index
* @param {number} end End index
* @returns {string} Processed string with comments replaced by whitespace
*/
const stripWithWhitespace = (string, start, end) =>
string.slice(start, end).replace(/[^ \t\r\n]/g, " ");
/**
* Check if a quote is escaped
* @param {string} jsonString JSON string
* @param {number} quotePosition Position of the quote
* @returns {boolean} True if the quote at the given position is escaped
*/
const isEscaped = (jsonString, quotePosition) => {
let index = quotePosition - 1;
let backslashCount = 0;
while (jsonString[index] === "\\") {
index -= 1;
backslashCount += 1;
}
return Boolean(backslashCount % 2);
};
/**
* Strip comments from JSON string
* @param {string} jsonString JSON string with potential comments
* @param {StripJsonCommentsOptions} options Options
* @returns {string} JSON string without comments
*/
function stripJsonComments(
jsonString,
{ whitespace = true, trailingCommas = false } = {},
) {
if (typeof jsonString !== "string") {
throw new TypeError(
`Expected argument \`jsonString\` to be a \`string\`, got \`${typeof jsonString}\``,
);
}
const strip = whitespace ? stripWithWhitespace : stripWithoutWhitespace;
let isInsideString = false;
/** @type {false | typeof singleComment | typeof multiComment} */
let isInsideComment = false;
let offset = 0;
let buffer = "";
let result = "";
let commaIndex = -1;
for (let index = 0; index < jsonString.length; index++) {
const currentCharacter = jsonString[index];
const nextCharacter = jsonString[index + 1];
if (!isInsideComment && currentCharacter === '"') {
// Enter or exit string
const escaped = isEscaped(jsonString, index);
if (!escaped) {
isInsideString = !isInsideString;
}
}
if (isInsideString) {
continue;
}
if (!isInsideComment && currentCharacter + nextCharacter === "//") {
// Enter single-line comment
buffer += jsonString.slice(offset, index);
offset = index;
isInsideComment = singleComment;
index++;
} else if (
isInsideComment === singleComment &&
currentCharacter + nextCharacter === "\r\n"
) {
// Exit single-line comment via \r\n
index++;
isInsideComment = false;
buffer += strip(jsonString, offset, index);
offset = index;
continue;
} else if (isInsideComment === singleComment && currentCharacter === "\n") {
// Exit single-line comment via \n
isInsideComment = false;
buffer += strip(jsonString, offset, index);
offset = index;
} else if (!isInsideComment && currentCharacter + nextCharacter === "/*") {
// Enter multiline comment
buffer += jsonString.slice(offset, index);
offset = index;
isInsideComment = multiComment;
index++;
continue;
} else if (
isInsideComment === multiComment &&
currentCharacter + nextCharacter === "*/"
) {
// Exit multiline comment
index++;
isInsideComment = false;
buffer += strip(jsonString, offset, index + 1);
offset = index + 1;
continue;
} else if (trailingCommas && !isInsideComment) {
if (commaIndex !== -1) {
if (currentCharacter === "}" || currentCharacter === "]") {
// Strip trailing comma
buffer += jsonString.slice(offset, index);
result += strip(buffer, 0, 1) + buffer.slice(1);
buffer = "";
offset = index;
commaIndex = -1;
} else if (
currentCharacter !== " " &&
currentCharacter !== "\t" &&
currentCharacter !== "\r" &&
currentCharacter !== "\n"
) {
// Hit non-whitespace following a comma; comma is not trailing
buffer += jsonString.slice(offset, index);
offset = index;
commaIndex = -1;
}
} else if (currentCharacter === ",") {
// Flush buffer prior to this point, and save new comma index
result += buffer + jsonString.slice(offset, index);
buffer = "";
offset = index;
commaIndex = index;
}
}
}
const remaining =
isInsideComment === singleComment
? strip(jsonString, offset, jsonString.length)
: jsonString.slice(offset);
return result + buffer + remaining;
}
module.exports = stripJsonComments;