Error with Javascript JSON.parse?

Question

console.log(JSON.parse('{"data":"{\"json\":\"rocks\"}"}')); 

gives an error (tested on the Firefox and Chrome console). Is this a bug with JSON.parse? It also decodes well when testing with PHP.

 print_r(json_decode('{"data":"{\"json\":\"rocks\"}"}', true)); 

Answer 1

This string is handled differently in PHP and JS, i.e. you get different results.

The only sequences of screens in single quotes in PHP are \\ and \' . All the rest are displayed literally, according to the documentation :

To specify a literal single quote, execute it with a backslash ( \ ). To specify a literal backslash, double it ( \\ ). All other instances of the backslash will be treated as a literal backslash: this means that other escape sequences that you might get used to, such as \r or \n , will be issued literally, as indicated, and not have any special value.

In JS, on the other hand, if the string contains an invalid escape sequence, the backslash is discarded ( CV stands for character value):

• CV CharacterEscapeSequence :: NonEscapeCharacter is a CV NonEscapeCharacter.
• CV NonEscapeCharacter :: SourceCharacter, but not EscapeCharacter or LineTerminator - this is the SourceCharacter character itself.

The quote may not be practical on its own, but if you follow the link and look at the grammar, it should become clear.

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So, in PHP, the string will literally contain \" , while in JS it will contain only " , which makes it invalid JSON:

 {"data":"{"json":"rocks"}"} 

If you want to create a literal backslash in JS, you need to avoid it:

 '{"data":"{\\"json\\":\\"rocks\\"}"}' 

Answer 2

To have a literal backslash in a string literal, you need \\ .

 console.log(JSON.parse('{"data":"{\\"json\\":\\"rocks\\"}"}')); 

This will successfully escape the internal quotes for handling JSON.

Answer 3

You need to avoid backslashes:

 console.log(JSON.parse('{"data":"{\\"json\\":\\"rocks\\"}"}'));​ 

Answer 4

You really don't need to avoid double quotes inside single quotes, and you have two extra quotes in the input around the inner object, just

 console.log(JSON.parse('{"data":{"json":"rocks"}}')); 

.

Answer 5

an object with a single '\' is not parsed by JSON.parser

myobj = {\ "json \": \ "rocks \"}

myobj = {\\ "json \\": \\ "rocks \\"}

Hinged lines worked for me

remove backslash

 while(typeof myobj == 'string'){ myobj = JSON.parse(myobj) }