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How to create a new object from the specified object, where all the keys are in lowercase in JavaScript?

  • Last Updated : 21 May, 2021

In this article, we will learn how to make a new object from the specified object where all the keys are in lowercase using JavaScript.

Example: 

Input: {RollNo : 1, Mark : 78}

Output: {rollno : 1, mark : 78}

Explanation: here, we have converted upper case to lower case keys values.



Approach 1: 

A simple approach is to Extract keys from Object and LowerCase to all keys and make Object with them. For this purpose we use Object.keys( ) to extract keys from object. And use String.toLowerCase() method to lower case keys and Array.reduce() method to make an object with lower-case strings. 

Example 1: 

HTML




<script>
  // Test Object
  const Student = { RollNo : 1, Mark: 78 };
  
  // Function to lowercase keys 
  function Conv( obj , key )
  {
    obj[key.toLowerCase()] = Student[key];
    return Student;
  }
  
  // Function to  create object from lowercase keys 
  function ObjKeys( obj) {
    let arr1 = Object.keys(obj);
    let ans = {};
    for(let i of arr1)
    {
    Conv(ans,i);
  
    }
    return ans;
  }
  
  a = ObjKeys(Student);
  console.log(a);
  
</script>

Output:

{ rollno : 1, mark : 78}

Approach 2:

The simplest approach is to convert Object to array and make keys to lower-case and make objects from a new array. For this purpose, we use Object.entries() to make an array from Object. And we use Array.map() to apply String.toLowerCase() method to all keys. To convert a new array to an Object we use Object.fromEntries().

Example:

HTML




<script>
  // Test Object
  const employ = { EmpId: 101, Batch: 56 };
  
  // Converting Object to array 
  let k = Object.entries(employ);
  
  //  Apply toLowerCase function to all keys 
  let l = k.map(function(t){
    t[0] = t[0].toLowerCase()
    return t;
    }
  );
  
  // Converting back array to Object
  const a  = Object.fromEntries(l)
  console.log(a)
</script>

Output:

{ empid : 101, batch : 56 } 



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