Question

I have a string in javascript:

var test = '{"test":"\\-"}'

When I try to parse this as JSON with the following:

JSON.parse(test)

or with:

$.parseJSON(test)

I get a SyntaxError of type “unexpected_token_number”.
This the value for the "test" attribute is a user enterable field. How should I properly escape this field?

Answer 1

'{"test":"\\-"}' will be interpreted as JavaScript string, with the result being {"test":"\-"}.

As you can see in these diagrams, \- is not a valid escape sequence (valid are \", \\, \/, \b, \f, \n, \r, \t, \uxxxx).

JSONLint also gives the error

Parse error on line 2:
{    "test": "\-"}
-------------^
Expecting 'STRING', 'NUMBER', 'NULL', 'TRUE', 'FALSE', '{', '['

If you want two backslashes in the JSON you have to escape them in the JavaScript string as well, so you’d end up with

var test = '{"test": "\\\\-"}';

Otherwise, omit it:

var test = '{"test": "-"}';