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Flatten JavaScript objects into a single-depth Object
  • Last Updated : 04 Mar, 2021

Given a nested JavaScript object, the task is to flatten the object and pull out all the values to a single depth. If the values are already at single depth then it returns the result unaltered.

typeof() method: The typeof() method is used in the script to check the type of JavaScript variable.



Parameters: This method accept one parameter as mentioned above and described below:

  • Variable: The input variable.

Return Value: This method returns a string which contains the type of the passed variable.


  1. We make a function called flatten object which takes input of an object and returns an object.
  2. Loop through the object and check the type of the current property:
    • If it is of type Object, recursively call the function again.
    • Otherwise, store the value in the result.
  3. Return the object.



// Declare an object
let ob = {
    Company: "GeeksforGeeks",
    Address: "Noida",
    contact: +91-999999999,
    mentor: {
        HTML: "GFG",
        CSS: "GFG",
        JavaScript: "GFG"
// Declare a flatten function that takes 
// object as parameter and returns the 
// flatten object
const flattenObj = (ob) => {
    // The object which contains the
    // final result
    let result = {};
    // loop through the object "ob"
    for (const i in ob) {
        // We check the type of the i using
        // typeof() function and recursively
        // call the function again
        if ((typeof ob[i]) === 'object') {
            const temp = flattenObj(ob[i]);
            for (const j in temp) {
                // Store temp in result
                result[i + '.' + j] = temp[j];
        // Else store ob[i] in result directly
        else {
            result[i] = ob[i];
    return result;


  Company: 'GeeksforGeeks',
  Address: 'Noida',
  contact: -999999908,
  'mentor.HTML': 'GFG',
  'mentor.CSS': 'GFG',
  'mentor.JavaScript': 'GFG'
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