Lets say I have object:

{
  cart: 4,
  trolley: 10,
  car: 2,
}

How can I turn it into:

{
  shopping_cart: 4,
  shopping_trolley: 10,
  shopping_car: 2,
}

Lets say I have object:

{
  cart: 4,
  trolley: 10,
  car: 2,
}

How can I turn it into:

{
  shopping_cart: 4,
  shopping_trolley: 10,
  shopping_car: 2,
}

• javascript
• object
• ecmascript-6

4 Answers 4

You can get the keys of the object in an array using the Object.keys() method. You can then use the Array.reduce() method to iterate over each of the keys and create a new object with desired prefix.

let obj = {
  cart: 4,
  trolley: 10,
  car: 2,
};

let pre = `shopping_`;

let nObj = Object.keys(obj).reduce((a, c) => (a[`${pre}${c}`] = obj[c], a), {});

console.log(nObj)

What have you tried so far?

var obj = {
  cart: 4,
  trolley: 10,
  car: 2
}

for (var key in obj) {
  obj["shopping_" + key] = obj[key]
  delete obj[key]
}

console.log(obj)

const createPrefixObjectKeys => prefix => source => {
  const prefixedSourceTuples = Object.entries(source).map(
    ([key, value]) => [
      `${prefix}${key}`,
       value
     ]
  );

  return Object.fromEntries(prefixedSourceTuples);
}

// use
const prefixObjectShopping = createPrefixObjectKeys('shopping_');

// where x is your object
const prefixed = prefixObjectShopping(x);

If you want to add keys even to nested objects in object. Use this (propably the easiest method)

function addKeyPrefixes(object, prefix){
    return JSON.parse(
        JSON.stringify(object).replace(/(?<=[{,]{1}\s*")(.+?)(?="\s*:)/gim, `${prefix}$1`)
    )
}

let obj = {
  'a' : {
    'b': 'c'
  },
  'd': 4
}

console.log(addKeyPrefixes(obj, '_'))

// {
//   '_a': {
//     '_b': 'c'
//   },
//   '_d': 4
// }