JSON.parse failing without reason

Question

I am using NodeJS, and the following JSON.parse is failing but I cant work out why:

> s[0]
'[["hands[0].session.buyin", "332"]]'
> JSON.parse(s[0]);
SyntaxError: Unexpected token 
    at Object.parse (native)
    at repl:1:6
    at REPLServer.self.eval (repl.js:110:21)
    at repl.js:249:20
    at REPLServer.self.eval (repl.js:122:7)
    at Interface.<anonymous> (repl.js:239:12)
    at Interface.EventEmitter.emit (events.js:95:17)
    at Interface._onLine (readline.js:202:10)
    at Interface._line (readline.js:531:8)
    at

The string in question has been loaded from a file. If I copy past the string into the console it works, so my suspicion is that it might be to do with the way the file is encoded, but I just cant work out what. JSON.parse's error messages are distinctly unhelpful.

You could try a JSON Lint service to make sure your JSON is valid. — Jasper
– Jasper, Commented Sep 24, 2013 at 17:38
What does the line look like in the file? Can you paste the contents? — Justin Ethier
– Justin Ethier, Commented Sep 24, 2013 at 17:41
JSON.parse('[["hands[0].session.buyin", "332"]]') works as expected. — Prinzhorn
– Prinzhorn, Commented Sep 24, 2013 at 17:44

Jonathan Lonowski · Accepted Answer · 2013-09-24 17:58:20Z

11

It seem that the String includes a Byte-Order Mark.

> s[0].charCodeAt(0).toString(16)
'feff'

You'll have to strip that out before JSON.parse() can manage the rest.

> JSON.parse(s[0].trim())
[ [ 'hands[0].session.buyin', '332' ] ]

edited Sep 24, 2013 at 17:58

answered Sep 24, 2013 at 17:47

Jonathan Lonowski

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1 Comment

gp. Over a year ago

This precisely is the problem.

leesei · Accepted Answer · 2013-09-24 17:44:39Z

1

On Node v0.10.12's REPL, this works fine:

> var b = '[["hands[0].session.buyin", "332"]]';
undefined
> JSON.parse(b)
[ [ 'hands[0].session.buyin', '332' ] ]
>

The string is a valid JSON representation of a 2D array.

What's your environment?

answered Sep 24, 2013 at 17:44

leesei

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