JSON: Uncaught SyntaxError: missing ) after argument list

Question

In a rails app I have an object defined in a controller containing an icon and some values:

@data = "<i class='fa fa-circle fa-lg'></i><span>Speed: </span> #{b.speed.to_f} | Time: #{b.gps_date.try(:strftime, '%-m/%e %H:%M')}} <br />".html_safe.to_json

In view I parse it like this:

<script>
  var data = JSON.parse('<%= raw @data.as_json %>');
</script>

But I get the following error:

Uncaught SyntaxError: missing ) after argument list

I works fine when I remove the icon code that contains the single quotes for class

<i class='fa fa-circle fa-lg'></i>

How can I fix this error?

Not a solution but just curious to know, why are you using to_json and as_json ? — Sajan
– Sajan, Commented Oct 21, 2016 at 11:14
I get the same error if I don't use these methods. I'm actually using this object in JavaScript so tried to_json and then parsed the json in JS — Arif
– Arif, Commented Oct 21, 2016 at 11:30
This does not look like a object. I guess you are trying to build a html node and pass it to JS then I guess only '<%= raw @data %>' should work. Have you tried ? — Sajan
– Sajan, Commented Oct 21, 2016 at 11:32
You're right. Removed all json parsing code and used just raw @data. It worked. Thanks for the help — Arif
– Arif, Commented Oct 21, 2016 at 11:38
I will post this as answer, if you want then you can accept it. — Sajan
– Sajan, Commented Oct 21, 2016 at 11:39

Sajan · Accepted Answer · 2016-10-21 12:24:19Z

2

You want to send the HTML string to JS so need of to_json, as this is used to convert Hash to JSON . So just use html_safe in server side.

And in client side, since you have the all HTML in string no need of as_json, just use the string as you would normally do in JS. as_json is a method used as ActiveRecord Serializer.

@data = "<i class='fa fa-circle fa-lg'></i><span>Speed: </span> #{b.speed.to_f} | Time: #{b.gps_date.try(:strftime, '%-m/%e %H:%M')}} <br />".html_safe

and

var data = <%= raw @data %>;

edited Oct 21, 2016 at 12:24

answered Oct 21, 2016 at 11:42

Sajan

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Sajan Over a year ago

Yes, I meant that. No need to parse as JSON since thats is a string. Forgot to remove while posting :)

evotopid · Accepted Answer · 2016-10-21 11:44:12Z

Basically this seems to be an issue with an unescaped ' popping up somewhere in JSON.parse('...'). You can verify the issue by looking at the HTML of the rendered page.

I think you might fix your issue by declaring (no need for the .to_json here):

@data = "<i class='fa fa-circle fa-lg'></i><span>Speed: </span> #{b.speed.to_f} | Time: #{b.gps_date.try(:strftime, '%-m/%e %H:%M')}} <br />".html_safe

And then in the view use

var data = "<%= escape_javascript @data %>";

as you are only tring to pass a string there is no need for the conversion into a JSON object and then parsing it back. (You'd need that if you wanted to pass a whole Javescript Object/Ruby Hash).

Actually for the last line there is also an equivalent shortcut/alias:

var data = "<%= j @data %>";

PS: I described how to fix the imminent issue but generally the point of MVC is to not have (or at least to minimize) presentation logic in a conroller. Generally it would be preferable to pass the data to the view and generate the HTML in the template.

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