How to De-Stringify Stringified JavaScript?

Question

How to 'de-stringify' JavaScript code that has been stringified? JSON.parse does not seem to work. We want to store JavaScript code in the database and then retrieve it and then eval it. Here's the code in the database:

//# sourceURL=journal.js

function onBlur(e) {

    var drAmount = script.getGridRowFieldValue('debitamount', e.rowuid)
    var crAmount = script.getGridRowFieldValue('creditamount', e.rowuid);

    // Prevent both debit and credit from having values.      
    if (drAmount != undefined && crAmount != undefined) {

        if (e.fieldname == 'debitamount') {
            script.setGridRowFieldValue('creditamount', e, undefined)
        } else if (e.fieldname == 'creditamount') {
            script.setGridRowFieldValue('debitamount', e, undefined)
        }

    }
}

Here's what's returned:

"//# sourceURL=journal.js\r\n\r\nexport function onBlur(e) {\r\n\r\n var drAmount = script.getGridRowFieldValue('debitamount', e.rowuid)\r\n var crAmount = script.getGridRowFieldValue('creditamount', e.rowuid);\r\n\r\n // Prevent both debit and credit from having values. \r\n if (drAmount != undefined && crAmount != undefined) {\r\n\r\n if (e.fieldname == 'debitamount') {\r\n script.setGridRowFieldValue('creditamount', e, undefined)\r\n } else if (e.fieldname == 'creditamount') {\r\n script.setGridRowFieldValue('debitamount', e, undefined)\r\n }\r\n\r\n }\r\n}\r\n\r\n\r\n\r\n\r\n"

Javascript is not JSON. It would be very strange if JSON.parse() helped you here. The eval() function is what you want, but be very careful not to eval() any "outside" code. There's a reason (more than one) that eval() is not a generally-recommended practice. — Paul Roub
– Paul Roub, Commented Apr 27, 2015 at 18:46
There's actually another issue beyond eval. In your returned minified block, I see terms like export function onBlur. That's not pure JavaScript - it might be part of some intermediary language like TypeScript or some ES6-inclusive compiler. — Katana314
– Katana314, Commented Apr 27, 2015 at 18:51

ekuusela · Accepted Answer · 2015-04-28 09:20:16Z

2

See eval. It accepts a string as a parameter, you could just pass that string into it and it should work.

Also, please read and understand the warnings mentioned by others and in the documentation I linked to.

edited Apr 28, 2015 at 9:20

answered Apr 27, 2015 at 18:47

ekuusela

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1 Comment

A2MetalCore Over a year ago

Totally and completely understand the risks!

Luan Nico · Accepted Answer · 2015-04-27 18:49:19Z

1

You should try to extract your object's behaviour from it's data. It's generally a bad thing to use eval, specially if you can't trust the string you are parsing. You should store the data as json, and the functions that consume the data should be static and be added to your object via prototype or something like that.

answered Apr 27, 2015 at 18:49

Luan Nico

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2 Comments

A2MetalCore Over a year ago

The entire product is customizable via JavaScript. Companies like ServiceNow and NetSuite use similar techniques. The risks are manageable.

Luan Nico Over a year ago

In that particular case then, if there is no way to 'standarize' the functions, eval might be your friend :)

Community · Accepted Answer · 2017-05-23 11:50:48Z

0

You should not JSON.stringify javascript code, only javascript data objects.

See this JSON.stringify function

Save the code as a string on your database. You might want to obfuscate your code. How can I obfuscate (protect) JavaScript?

edited May 23, 2017 at 11:50

CommunityBot

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answered Apr 27, 2015 at 18:51

Peheje

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1 Comment

A2MetalCore Over a year ago

The REST API stringified the data.

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