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JSON.parse() fails when a string contains the "null" substring… for example with italian words like "annullo" or "annullare"

Good morning everyone and thank you in advance for any suggestions. I have written a small web application to perform simple searches in a stamps database using php and javascript.

The server sends to the browser the whole database as a JSON and the queries are done client-side with a javascript code.
The JSON has this structure:
{"ck":0,"db":[["string11","string12","string13"],["string21","string22","string23"], etc... } .

Until now the system has worked perfectly and over 1500 stamps could be shown.
Suddenly it stopped working and, in the browser’s Javascript console, this error message appeared:
VM672:1 Uncaught SyntaxError: Expected ',' or ']' after array element in JSON at position 97506 at JSON.parse (<anonymous>) ...etc...

After a series of tests, by exclusion I came to discover that it was the word "annullo" in the last added record to generate the error.

I guess it could be the substring "null" to give problems, but I have no idea how to escape it.
A really strange thing is that, whilst failing with the JSON.parse() function, browser’s javascript console, as well as other json validation tools, recognise the server’s response as a valid JSON.

Thanks for any help!

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2

Answers


  1. 0

    I think I understand the problem. All strings are enclosed in quotes.

    {example: "example"}

    In the development of this case they must have put "annullo" but they forgot to insert the quotes. If it was null, not a string, it could look like this, without quotes.

    json = {example: null}

    However, as annullo is an invalid word in javascript and is not as a string, it gives an error.

    The correct thing to do is to correct the error in the source, transforming it to null, however, I believe that you can also use this regular expression. But do tests to ensure that there is no undue substitution elsewhere.

    json.replace(/.+["']: ?annull(o|are)[n,}]$/g, matched => {
    return matched.replace(/annull(o|are)/, 'null')
})
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  2. 0

    As @Andrea Soffiantini pointed in a comment, this was the actual problem:

    Client side I had this command a few lines before parsing: data = data.replaceAll("null",""""); , where data is the json as a string, as received from server.

    This replaces the string "anullo" with "a""o", which is invalid in JSON syntax.

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