I have this line in a javascript block in a page:
res = foo('<%= @ruby_var %>');
What is the best way to handle the case where @ruby_var has a single-quote in it? Else it will break the JavaScript code.
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7 Answers
I think I'd use a ruby JSON library on @ruby_var to get proper js syntax for the string and get rid of the '', fex.:
res = foo(<%= @ruby_var.to_json %>)
(after require "json"'ing, not entirely sure how to do that in the page or if the above syntax is correct as I havn't used that templating language)
(on the other hand, if JSON ever changed to be incompatible with js that'd break, but since a decent amount of code uses eval() to eval json I doubt that'd happen anytime soon)
2 Comments
Grant Hutchins
Rails already comes with String#to_json, so you don't even need to include any libraries: api.rubyonrails.com/classes/Object.html#M000022
akxer
.to_json adds html quotes(") to my string
Rails has method specifically dedicated to this task found in ActionView::Helpers::JavaScriptHelper called escape_javascript.
In your example, you would use the following:
res = foo('<%= escape_javascript @ruby_var %>');
Or better yet, use the j shortcut:
res = foo('<%= j @ruby_var %>');
Comments
@ruby_var.gsub(/[']/, '\\\\\'')
That will escape the single quote with an apostrophe, keeping your Javascript safe!
Also, if you're in Rails, there are a bunch of Javascript-specific tools.
Could you just put the string in a double-quote?
res = foo("<%= @ruby_var %>");
1 Comment
Yoni Baciu
but then what if @ruby_var has a double quote in it?
You can also use inspect assuming you know it'll be a single quote:
res = foo(<%= @ruby_var.inspect %>);
Comments
I don't work with embedded Ruby too much. But how about using p (which invokes inspect) instead of <%= which might be doing something like print or puts. p always prints the string as if it were code wrapped in double quotes:
>> p "String ' \" String"
"String ' \" String"
# => nil
>> p 'alpha " \' alpha'
"alpha \" ' alpha"
# => nil
Comments
You may want to use the following first property, to get rid of the " from your string and then you can go ahead and use your json function.
res = foo('<%= @ruby_var %>.first');
