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I am creating a Angular 2 application. My server side request returns me a JSON that will look like

[{"CountryId":1,"CountryCode":"IND","CountryName":"India","State":[]},
 {"CountryId":2,"CountryCode":"AUS","CountryName":"Australia","State":[]}]

I need to display this in a dropdown. So I need to create a new JSON that will look like

[{"Label":"India","Value":"IND"},
{"Label":"Australia","Value":"AUS"}]

I dont want to write for loop as i will be using this in many places and i want it to be best possible in performance. Please let me know if there is any inbuilt function that can do this kind of JSON restructure.

I am creating a Angular 2 application. My server side request returns me a JSON that will look like

[{"CountryId":1,"CountryCode":"IND","CountryName":"India","State":[]},
 {"CountryId":2,"CountryCode":"AUS","CountryName":"Australia","State":[]}]

I need to display this in a dropdown. So I need to create a new JSON that will look like

[{"Label":"India","Value":"IND"},
{"Label":"Australia","Value":"AUS"}]

I dont want to write for loop as i will be using this in many places and i want it to be best possible in performance. Please let me know if there is any inbuilt function that can do this kind of JSON restructure.

• javascript
• json
• typescript

Share Improve this question Follow edited Aug 21, 2016 at 7:39 Toby Allen 11.2k1212 gold badges7979 silver badges131131 bronze badges asked Aug 21, 2016 at 3:05 VinodVinod 32.9k3535 gold badges9999 silver badges119119 bronze badges 6

• 2 Are you sure you need to transform the JSON? Cannot the UI ponent be configured to use alternate keys for label and value? – Thilo Commented Aug 21, 2016 at 3:10
• 3 A for loop is exactly what you need (although map() is nicer). – SLaks Commented Aug 21, 2016 at 3:11
• @Thilo I am using custom library primeng. This probably does not support for now. – Vinod Commented Aug 21, 2016 at 3:16
• Sometimes you just have to write some code darnit! – Toby Allen Commented Aug 21, 2016 at 7:34
• 1 You don't really want to create new JSON. I assume you're converting the JSON resturned to a javascript array and want to convert the objects in the array to objects with different properties. Using JSON in your title and using the JSON tag makes it seem like you are talking about JSON in particular (JavaScript Object Notation), the string representation of javascript objects. – Jason Goemaat Commented Aug 21, 2016 at 12:16

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2 Answers 2

Sorted by: Reset to default 6

Unless you know exactly how many elements there will be in your response array you can't escape from iterating it, although you can choose how:

// A
let result = response.map((elem) => ({
  'Label': elem.CountryName,
  'Value': elem.CountryCode
}))


// B
let result = []

response.forEach((elem) =>
  result.push({
    'Label': elem.CountryName,
    'Value': elem.CountryCode
  })
)


// C
let result = []

for (i in response) {
  result.push({
    'Label': response[i]['CountryName'],
    'Value': response[i]['CountryCode']
  })
)

Using ES6 destructuring, the most pact form would be:

 response.map(({CountryCode: Label, CountryName: Value}) => ({Label, Value}))

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