I encountered an issue while attempting to manipulate/retrieve the JSON value using REGEX, resulting in an undefined return

Question

I encountered an issue while attempting to manipulate/retrieve the JSON value using REGEX, resulting in an undefined return

I am attempting to retrieve the currency value from a JSON file and if it is USD, then I want to change it to AUD.

When trying to find the currency attribute in the JSON file, it returned 'undefined' as shown below:

Code:

var datastring = JSON.stringify(data);
var match = /"currency":(^")*/.exec(datastring);
console.log(match ? "Got " + match[1] : "No match");

Output: Got undefined

data.json:

{
   "bank":[
      {
         "bankAccountType":"Saving",
         "country":"US",
         "currency":"USD",
         "firstName":"TestFirstName",
         "lastName":"TestLastName",
         "confirmed":"true"
      }
   ]
}

Could someone assist me on how to update the currency value in the JSON file and why it is returning 'undefined'?

Thank you for your help.

Updated:

The data.json file is dynamic, with its structure changing every few minutes. My focus is solely on retrieving the currency attribute which is always present in the data.json file and updating the JSON before sending it to the server.

javascript json regex

Answer 1

Answer №1

The regular expression seems to be incorrect. You may want to attempt using

/"currency":"([^"]*)"/

.

Answer 2

The regular expression seems to be incorrect. You may want to attempt using

/"currency":"([^"]*)"/

.

Answer 3

Answer №2

When dealing with structured data like JSON, performing a string match may lead to more issues than solutions. If the data follows a consistent structure, it is best to manipulate it based on that structure. On the other hand, if the data is not consistently structured, relying on string manipulation can be unreliable.

Although your regex pattern is simple, it contains some errors:

/"currency":(^")*/

"currency": will match exactly as written (assuming no extra whitespace)
(: starts a capturing group
^: indicates the start of the string, which is incorrect in this context
": matches a literal "
)*: ends the capturing group and allows for zero or more occurrences

It seems like you intended to use [^"] instead of (^"), meaning "any character except "". However, this would not work due to the " immediately following the colon.

Consider using + instead of * for "one or more", or specifying the exact number of characters using {3}.

To capture the entire 3-character currency code, ensure the brackets encapsulate the full expression:

/"currency":"([^"]+)"/

You could also simplify the pattern by using three wildcard characters:

/"currency":"(...)"/

Answer 4

When dealing with structured data like JSON, performing a string match may lead to more issues than solutions. If the data follows a consistent structure, it is best to manipulate it based on that structure. On the other hand, if the data is not consistently structured, relying on string manipulation can be unreliable.

Although your regex pattern is simple, it contains some errors:

/"currency":(^")*/

"currency": will match exactly as written (assuming no extra whitespace)
(: starts a capturing group
^: indicates the start of the string, which is incorrect in this context
": matches a literal "
)*: ends the capturing group and allows for zero or more occurrences

It seems like you intended to use [^"] instead of (^"), meaning "any character except "". However, this would not work due to the " immediately following the colon.

Consider using + instead of * for "one or more", or specifying the exact number of characters using {3}.

To capture the entire 3-character currency code, ensure the brackets encapsulate the full expression:

/"currency":"([^"]+)"/

You could also simplify the pattern by using three wildcard characters:

/"currency":"(...)"/

Answer 5

Answer №3

Here is a sample of how this can be accomplished.

let information = {
   "bank":[
      {
         "accountType":"Savings",
         "country":"US",
         "currency":"USD",
         "firstName":"John",
         "lastName":"Doe",
         "verified":"true"
      }
   ]
};

var dataString = JSON.stringify(information);

console.log(dataString);

var match = /"currency":\"[A-Z]{3}\"/.exec(dataString)[0];

let currencyValue = match.split(":")[1].replaceAll('"', '');

console.log(currencyValue);

//You can also access the currency directly from the data

console.log(information.bank[0].currency);

//If the data is in string format, you can use the JSON.parse() function to convert it into a JSON object.

//https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/JSON/parse

//Assuming that you have the JSON as a string:

let jsonObject = JSON.parse(dataString);

console.log(jsonObject.bank[0].currency);

//To replace USD with AUD for example:

jsonObject.bank[0].currency = jsonObject.bank[0].currency.replace("USD", "AUD");

console.log(jsonObject.bank[0].currency);

Answer 6

Here is a sample of how this can be accomplished.

let information = {
   "bank":[
      {
         "accountType":"Savings",
         "country":"US",
         "currency":"USD",
         "firstName":"John",
         "lastName":"Doe",
         "verified":"true"
      }
   ]
};

var dataString = JSON.stringify(information);

console.log(dataString);

var match = /"currency":\"[A-Z]{3}\"/.exec(dataString)[0];

let currencyValue = match.split(":")[1].replaceAll('"', '');

console.log(currencyValue);

//You can also access the currency directly from the data

console.log(information.bank[0].currency);

//If the data is in string format, you can use the JSON.parse() function to convert it into a JSON object.

//https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/JSON/parse

//Assuming that you have the JSON as a string:

let jsonObject = JSON.parse(dataString);

console.log(jsonObject.bank[0].currency);

//To replace USD with AUD for example:

jsonObject.bank[0].currency = jsonObject.bank[0].currency.replace("USD", "AUD");

console.log(jsonObject.bank[0].currency);

Answer 7

Answer №4

To convert currency from USD to AUD, you can utilize the following regex;

/(?<="currency":")[^"]+/

const data = {
  bank: [{
    bankAccountType: "Saving",
    country: "US",
    currency: "USD",
    firstName: "TestFirstName",
    lastName: "TestLastName",
    confirmed: "true",
  }, ],
};

var datastring = JSON.stringify(data);
const replacedString = datastring.replace(/(?<="currency":")[^"]+/, "AUD");
console.log(replacedString);

Answer 8

To convert currency from USD to AUD, you can utilize the following regex;

/(?<="currency":")[^"]+/

const data = {
  bank: [{
    bankAccountType: "Saving",
    country: "US",
    currency: "USD",
    firstName: "TestFirstName",
    lastName: "TestLastName",
    confirmed: "true",
  }, ],
};

var datastring = JSON.stringify(data);
const replacedString = datastring.replace(/(?<="currency":")[^"]+/, "AUD");
console.log(replacedString);

Answer 9

Answer №5

let userData = {
  customer: [
    {
      userType: 'Guest',
      country: 'Canada',
      currency: 'CAD',
      firstName: 'John',
      lastName: 'Doe',
      confirmed: 'true'
    }
  ]
}
let userDataString = JSON.stringify(userData)
let updatedCurrency = userDataString.replace(/"currency":"([^"]*)"/, '"currency":"EUR"')
let parsedData = JSON.parse(updatedCurrency)
console.log(parsedData)

Answer 10

let userData = {
  customer: [
    {
      userType: 'Guest',
      country: 'Canada',
      currency: 'CAD',
      firstName: 'John',
      lastName: 'Doe',
      confirmed: 'true'
    }
  ]
}
let userDataString = JSON.stringify(userData)
let updatedCurrency = userDataString.replace(/"currency":"([^"]*)"/, '"currency":"EUR"')
let parsedData = JSON.parse(updatedCurrency)
console.log(parsedData)

I encountered an issue while attempting to manipulate/retrieve the JSON value using REGEX, resulting in an undefined return

Answer №1

Answer №2

Answer №3

Answer №4

Answer №5

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