I'm appalled by the presence of highly-upvoted misinformation on such a highly-viewed question about a basic topic.
JSON strings cannot be quoted with single quotes. The various versions of the spec (the original by Douglas Crockford, the ECMA version, and the IETF version) all state that strings must be quoted with double quotes. This is not a theoretical issue, nor a matter of opinion as the accepted answer currently suggests; any JSON parser in the real world will error out if you try to have it parse a single-quoted string.
Crockford's and ECMA's version even display the definition of a string using a pretty picture, which should make the point unambiguously clear:
The pretty picture also lists all of the legitimate escape sequences within a JSON string:
\"\\\/\b\f\n\r\t\ufollowed by four-hex-digits
Note that, contrary to the nonsense in some other answers here, \' is never a valid escape sequence in a JSON string. It doesn't need to be, because JSON strings are always double-quoted.
Finally, you shouldn't normally have to think about escaping characters yourself when programatically generating JSON (though of course you will when manually editing, say, a JSON-based config file). Instead, form the data structure you want to encode using whatever native map, array, string, number, boolean, and null types your language has, and then encode it to JSON with a JSON-encoding function. Such a function is probably built into whatever language you're using, like JavaScript's JSON.stringify, PHP's json_encode, or Python's json.dumps. If you're using a language that doesn't have such functionality built in, you can probably find a JSON parsing and encoding library to use. If you simply use language or library functions to convert things to and from JSON, you'll never even need to know JSON's escaping rules. This is what the misguided question asker here ought to have done.
I'm appalled by the presence of highly-upvoted misinformation on such a highly-viewed question about a basic topic.
JSON strings cannot be quoted with single quotes. The various versions of the spec (the original by Douglas Crockford, the ECMA version, and the IETF version) all state that strings must be quoted with double quotes. This is not a theoretical issue, nor a matter of opinion as the accepted answer currently suggests; any JSON parser in the real world will error out if you try to have it parse a single-quoted string.
Crockford's and ECMA's version even display the definition of a string using a pretty picture, which should make the point unambiguously clear:
The pretty picture also lists all of the legitimate escape sequences within a JSON string:
\"\\\/\b\f\n\r\t\ufollowed by four-hex-digits
Note that, contrary to the nonsense in some other answers here, \' is never a valid escape sequence in a JSON string. It doesn't need to be, because JSON strings are always double-quoted.
Finally, you shouldn't normally have to think about escaping characters yourself when programatically generating JSON (though of course you will when manually editing, say, a JSON-based config file). Instead, form the data structure you want to encode using whatever native map, array, string, number, boolean, and null types your language has, and then encode it to JSON with a JSON-encoding function. Such a function is probably built into whatever language you're using, like JavaScript's JSON.stringify, PHP's json_encode, or Python's json.dumps. If you're using a language that doesn't have such functionality built in, you can probably find a JSON parsing and encoding library to use. If you simply use language or library functions to convert things to and from JSON, you'll never even need to know JSON's escaping rules. This is what the misguided question asker here ought to have done.
A JSON string must be double-quoted, according to the specs, so you don't need to escape '.
If you have to use special character in your JSON string, you can escape it using \ character.
See this list of special character used in JSON :
\b Backspace (ascii code 08)
\f Form feed (ascii code 0C)
\n New line
\r Carriage return
\t Tab
\" Double quote
\\ Backslash character
However, even if it is totally contrary to the spec, the author could use \'.
This is bad because :
- It IS contrary to the specs
- It is no-longer JSON valid string
But it works, as you want it or not.
For new readers, always use a double quotes for your json strings.
Videos
Can I use any special character in a key name in JSON? For example, is the following JSON valid?
{
"studentName": "John Doe",
"studentGrade": "9",
"marksIn%": "82"
}
Take a look at http://json.org/. It claims a bit different list of escaped characters than Chris proposed.
\"
\\
\/
\b
\f
\n
\r
\t
\u four-hex-digits
Here is a list of special characters that you can escape when creating a string literal for JSON:
\b Backspace (ASCII code 08) \f Form feed (ASCII code 0C) \n New line \r Carriage return \t Tab \v Vertical tab \' Apostrophe or single quote \" Double quote \\ Backslash character
Reference: String literals
Some of these are more optional than others. For instance, your string should be perfectly valid whether you escape the tab character or leave in a tab literal. You should certainly be handling the backslash and quote characters, though.
So I have a new line delimited JSON
{
"foo-bar":"foo-baar",
"foob@r":"bar.foo",
"b.a.r":"foo"
}should be normalized to
{
"foobar":"foo-baar",
"foobr":"bar.foo",
"bar":"foo"
}so it has replaced special characters in the keys (. @ -) in my example.
I am using PCRE