Adding a unique id for each entry in JSON object in JavaScript

In this problem statement, our task is to add a unique id for every object entry in a JSON object with the help of JavaScript. We will use a loop and a variable to store the id for each object in the JSON object.

Understanding the Problem Statement

The problem statement is to write a function in JavaScript that adds a unique id to every item in the given JSON object. For example, if we have:

let obj = {
   "entry1": {empName: "A", age: 25},
   "entry2": {empName: "B", age: 30}
};

After adding unique ids, the updated object will be:

let obj = {
   "entry1": {id: 0, empName: "A", age: 25},
   "entry2": {id: 1, empName: "B", age: 30}
};

Method 1: Using for...in Loop

This approach iterates through each key in the object and adds an incremental id property.

const jsonData = {
   "entry1": {
      "empName": "Janvi",
      "age": 30
   },
   "entry2": {
      "empName": "Rani",
      "age": 25
   },
   "entry3": {
      "empName": "Babita",
      "age": 40
   }
};

// Function to add unique ID to JSON object
function addUniqueId(jsonData) {
   let index = 0;
   for (let key in jsonData) {
      jsonData[key].id = index++;
   }
   return jsonData;
}

const resultObject = addUniqueId(jsonData);
console.log(resultObject);

{
  entry1: { empName: 'Janvi', age: 30, id: 0 },
  entry2: { empName: 'Rani', age: 25, id: 1 },
  entry3: { empName: 'Babita', age: 40, id: 2 }
}

Method 2: Using Object.keys() with forEach

This method uses Object.keys() to get all keys and then iterates using forEach to add unique ids.

const jsonData2 = {
   "user1": { "name": "Alice", "role": "admin" },
   "user2": { "name": "Bob", "role": "user" },
   "user3": { "name": "Charlie", "role": "moderator" }
};

function addUniqueIdWithKeys(data) {
   const keys = Object.keys(data);
   keys.forEach((key, index) => {
      data[key].id = index + 1; // Starting from 1
   });
   return data;
}

const result2 = addUniqueIdWithKeys(jsonData2);
console.log(result2);

{
  user1: { name: 'Alice', role: 'admin', id: 1 },
  user2: { name: 'Bob', role: 'user', id: 2 },
  user3: { name: 'Charlie', role: 'moderator', id: 3 }
}

Method 3: Using UUID for Unique IDs

For truly unique identifiers, you can generate UUIDs or timestamp-based IDs:

const jsonData3 = {
   "product1": { "name": "Laptop", "price": 999 },
   "product2": { "name": "Mouse", "price": 25 }
};

function addUUIDLikeId(data) {
   for (let key in data) {
      // Generate a simple unique ID using timestamp and random number
      data[key].id = Date.now().toString(36) + Math.random().toString(36).substr(2);
   }
   return data;
}

const result3 = addUUIDLikeId(jsonData3);
console.log(result3);

{
  product1: { name: 'Laptop', price: 999, id: 'lm8j9k2n3p4q5' },
  product2: { name: 'Mouse', price: 25, id: 'lm8j9k2n3r6s7' }
}

Comparison

Complexity Analysis

Time Complexity: O(n), where n is the number of entries in the JSON object, as we need to iterate through each entry once.

Space Complexity: O(1) if modifying in place, or O(n) if creating a new object with the IDs.

Conclusion

Adding unique IDs to JSON objects is straightforward using loops. Choose incremental IDs for simple cases or UUID-like strings for globally unique identifiers. All methods have O(n) time complexity and are efficient for most use cases.