Flatten JavaScript objects into a single-depth Object
Last Updated :
14 Oct, 2025
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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 a single depth then it returns the result unaltered.
[Approach]: Using typeof()
- The typeof() method is used in the script to check the type of JavaScript variable.
- The
Variableparameter represents the input value to be checked, and the method returns a string indicating the type of that variable.
How it works:
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 and it is not an Array, 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' && !Array.isArray(ob[i])) {
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;
};
console.log(flattenObj(ob));
Output
{
Company: 'GeeksforGeeks',
Address: 'Noida',
contact: -999999908,
'mentor.HTML': 'GFG',
'mentor.CSS': 'GFG',
'mentor.JavaScript': 'GFG'
}
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