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Javascript – How to parse JSON string with escape characters

I have a JSON string like this:

'{"text": "Given that \( a \)"}'

Please note that I cannot remove any backslashes. Text property needs to rendered as a maths equation. That’s why there are latex delimiters in JSON string. How to parse this string without affecting backslashes?

Expected output (dictionry or object) : {"text": "Given that \( a \)"}

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2

Answers


  1. 0 
    let q = '{"text": "Given that \\ ( a \\ )"}';
let json = JSON.parse(q);

console.log(json);

    The reason for using four backslashes is due to the fact that when defining a string in JavaScript, you need to escape the backslash itself. So, when you want to include a single backslash in the resulting string, you need to escape it with another backslash.

    In your case, you want to include "(" and ")" in the string, where each "" represents a single backslash. Therefore, you need to escape each backslash with another backslash, resulting in four backslashes:

    The first two backslashes represent the escape sequence for a single backslash in the resulting string.
    The next two backslashes represent the actual backslash characters you want in the string.
    So, when you parse the JSON, it correctly interprets the escaped backslashes as literal backslashes in the string. If you only use two backslashes, it may not be interpreted correctly, leading to a syntax error.

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  2. 0

    TL;DR Either the string object was not defined properly, or you are just misinterpreting how the string is displayed.

    If you have code like

    x = '{"text": "Given that \( a \)"}'

    then x does not contain a valid JSON object. In a normal string literal, the \ is treated as a digraph that results in a literal backslash character:

    >>> print(x)
{"text": "Given that ( a )"}
>>> json.loads(x)
[...]
json.decoder.JSONDecodeError: Invalid escape: line 1 column 22 (char 21)

    Knowing what JSON object you want, the simplest solution is to use a raw-string literal to prevent Python from processing the escaped backslash before a literal \ can be used to construct the actual JSON.

    >>> x = r'{"text": "Given that \( a \)"}'
>>> print(x)
{"text": "Given that \( a \)"}
>>> json.loads(x)
{'text': 'Given that \( a \)'}

    The double backslashes you see here aren’t "in" the string; it’s just how they appear in the string representing the dict. If you print just the string, you’ll see the single backslashes that LaTeX would expect.

    >>> print(json.loads(x)['text'])
Given that ( a )
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