在JavaScript和Python 2.7中的JSON字符串中转义反斜杠

Question

Here is my JSON string to loads or Parse:

json_str = '[{"executable_path": "C:\\GCafeClient\\CafeClient.exe", "arguments": "-package 100003"}]'

This was valid if I test it in json formatter or here (Also it makes sense right--I have escaped backslash.

But when I do json.loads(json_str) in Python 2.7 or JSON.parse(json_str) in JavaScript in Chrome. I got errors:

ValueError: Invalid \escape: line 1 column 25 (char 24)

and

Uncaught SyntaxError: Unexpected token G

If I put it this way, then it will work for both:

json_str = '[{"executable_path": "C:\\\\GCafeClient\\\\CafeClient.exe", "arguments": "-package 100003"}]'

Why is this so?

Answer 1

I will just post my own understanding here for this question:

# python
json_str = '[{"executable_path": "C:\\\\GCafeClient\\\\CafeClient.exe", "arguments": "-package 100003"}]'
# which is equivalent to
json_str = r'[{"executable_path": "C:\\GCafeClient\\CafeClient.exe", "arguments": "-package 100003"}]'
# and JSON format requires backslash to be escaped

Answer 2

You need to escape the '\\' twice, the first time for the Python/JavaScript literal and the second time for JSON.

So "C:\\\\GCafeClient" will evaluate to "C:\\GCafeClient" , which is not accepted JSON as it contains an unescaped '\\' and will throw an error.

On the other hand "C:\\\\\\\\GCafeClient" will evaluate to the JSON being "C:\\\\GCafeClient" , therefore the '\\' is escaped and accepted.