Failing to parse this valid JSON

[stephen147]

var str = '{ "kind": "youtube#playlistItemListResponse", "etag": "p4VTdlkQv3HQeTEaXgvLePAydmU/Vc3EkgLSTjYGqvhPMXul5T13c6k", "pageInfo": { "totalResults": 19, "resultsPerPage": 50 }, "items": [ { "kind": "youtube#playlistItem", "etag": "p4VTdlkQv3HQeTEaXgvLePAydmU/7hcDWTrN7EFhot4DpXw8fi97qUo", "id": "UExvQXI3RzlNaGtuOG1jTTR2VjE4SlY1RG5EMnJLQUYxNC5CMUM0NzY5NzdEQzlGRjAx", "snippet": { "publishedAt": "2019-12-23T17:23:10.000Z", "channelId": "UCaSq01bKPGAmrOnjpzBFDPQ", "title": "Regal - Repeat", "description": "Released by: Involve Records \n\nRelease/catalogue number: INV008 \n\nRelease date: Jun 15, 2015\n\nBuy and support\nhttp://decks.de/t/regal-alma_mater_ep/c55-r6\n\nhttp://facebook.com/RegalOfficial\nhttp://soundcloud.com/regalmusic\n\nhttp://involverecords.es\nhttp://facebook.com/involverecords\nhttp://soundcloud.com/involve-records\n\nRegal is back on his own imprint with a 4 cuts powerful EP. Two acid cuts, as couldn’t be otherwise, plus two dark, but full of soul, techno tracks for the mental moment of the night.\n\nAll rights reserved for the producers of these tracks.", "thumbnails": { "default": { "url": "https://i.ytimg.com/vi/7QPrJa7z12s/default.jpg", "width": 120, "height": 90 }, "medium": { "url": "https://i.ytimg.com/vi/7QPrJa7z12s/mqdefault.jpg", "width": 320, "height": 180 }, "high": { "url": "https://i.ytimg.com/vi/7QPrJa7z12s/hqdefault.jpg", "width": 480, "height": 360 }, "standard": { "url": "https://i.ytimg.com/vi/7QPrJa7z12s/sddefault.jpg", "width": 640, "height": 480 }, "maxres": { "url": "https://i.ytimg.com/vi/7QPrJa7z12s/maxresdefault.jpg", "width": 1280, "height": 720 } }, "channelTitle": "Channelxyz", "playlistId": "PLoAr7G9Mhkn8mcM4vV18JV5DnD2rKAF14", "position": 0, "resourceId": { "kind": "youtube#video", "videoId": "7QPrJa7z12s" } }, "contentDetails": { "videoId": "7QPrJa7z12s", "videoPublishedAt": "2015-07-02T15:07:27.000Z" } } ] }';
var obj = JSON.parse(str, function (key, value) {
return value;
});
console.log(obj.etag);

The above is failing to parse. Is this user error or something else that may be causing it to fail.

The JSON str variable is valid using an online checker.

The error that's getting returned is:

SyntaxError: Unexpected token 
 in JSON at position 530
    at JSON.parse (<anonymous>)

[jamesearl]

Seems a conflict with the newline escapes and your interpreter vs json linter. It's valid JSON if you drop the single quote wrapping and test it, but when the interpreter grabs the string it handles the \n escapes ahead of the JSON.parse call.

You fix it by escaping the backslash ahead of the newline escapes: \\n

[stephen147]

I don't quite understand, you mean inside the json2.js

[jamesearl]

No there's nothing wrong with json2.js

I'm saying that the string you're parsing is not the string you think you're parsing, because of the newline (\n) characters.

This fails for the same reason that your input string does: JSON.parse('{"a": "\n"}')

[jamesearl]

See this: https://stackoverflow.com/questions/42068/how-do-i-handle-newlines-in-json

[stephen147]

Ok, by doing this it worked. I thought that it was a bug but going by that thread it's by design.

Here's the fix:

String.prototype.jsonEscape = function() {
return this.replace(/\n/g, "\\\\n").replace(/\r/g, "\\\\r").replace(/\t/g, "\\\\t");
}

var str = '{ "kind": "youtube#playlistItemListResponse", "etag": "p4VTdlkQv3HQeTEaXgvLePAydmU/Vc3EkgLSTjYGqvhPMXul5T13c6k", "pageInfo": { "totalResults": 19, "resultsPerPage": 50 }, "items": [ { "kind": "youtube#playlistItem", "etag": "p4VTdlkQv3HQeTEaXgvLePAydmU/7hcDWTrN7EFhot4DpXw8fi97qUo", "id": "UExvQXI3RzlNaGtuOG1jTTR2VjE4SlY1RG5EMnJLQUYxNC5CMUM0NzY5NzdEQzlGRjAx", "snippet": { "publishedAt": "2019-12-23T17:23:10.000Z", "channelId": "UCaSq01bKPGAmrOnjpzBFDPQ", "title": "Regal - Repeat", "description": "Released by: Involve Records \n\nRelease/catalogue number: INV008 \n\nRelease date: Jun 15, 2015\n\nBuy and support\nhttp://decks.de/t/regal-alma_mater_ep/c55-r6\n\nhttp://facebook.com/RegalOfficial\nhttp://soundcloud.com/regalmusic\n\nhttp://involverecords.es\nhttp://facebook.com/involverecords\nhttp://soundcloud.com/involve-records\n\nRegal is back on his own imprint with a 4 cuts powerful EP. Two acid cuts, as couldn’t be otherwise, plus two dark, but full of soul, techno tracks for the mental moment of the night.\n\nAll rights reserved for the producers of these tracks.", "thumbnails": { "default": { "url": "https://i.ytimg.com/vi/7QPrJa7z12s/default.jpg", "width": 120, "height": 90 }, "medium": { "url": "https://i.ytimg.com/vi/7QPrJa7z12s/mqdefault.jpg", "width": 320, "height": 180 }, "high": { "url": "https://i.ytimg.com/vi/7QPrJa7z12s/hqdefault.jpg", "width": 480, "height": 360 }, "standard": { "url": "https://i.ytimg.com/vi/7QPrJa7z12s/sddefault.jpg", "width": 640, "height": 480 }, "maxres": { "url": "https://i.ytimg.com/vi/7QPrJa7z12s/maxresdefault.jpg", "width": 1280, "height": 720 } }, "channelTitle": "Channelxyz", "playlistId": "PLoAr7G9Mhkn8mcM4vV18JV5DnD2rKAF14", "position": 0, "resourceId": { "kind": "youtube#video", "videoId": "7QPrJa7z12s" } }, "contentDetails": { "videoId": "7QPrJa7z12s", "videoPublishedAt": "2015-07-02T15:07:27.000Z" } } ] }';
var str = str.jsonEscape();

var obj = JSON.parse(str, function (key, value) {
return value;
});
console.log(obj.etag);
// p4VTdlkQv3HQeTEaXgvLePAydmU/Vc3EkgLSTjYGqvhPMXul5T13c6k

Thanks for your help, James.

[douglascrockford]

It is not safe to add stuff to the system's prototypes. A better solution is to use JSON.stringify. Happy new year.

[stephen147]

Thanks for the tip, Douglas. Happy new year to you also!