Syntax error Combining the identical entries together in JavaScript

Combining the identical entries together in JavaScript

We have an array of numbers that have got identical entries. We are required to write a function that takes in the array and groups all the identical entries into one subarray and returns the new array thus formed.

For example: If the input array is −

const arr = [234, 65, 65, 2, 2, 234];

// then the output should be −

const output = [[234, 234], [65, 65], [2, 2]];

We will use a Hashmap to keep a track of the elements already occurred and iterate over the array using a for loop.

Therefore, let’s write the code for this function −

Example

The code for this will be −

const arr = [234, 65, 65, 2, 2, 234];
const groupArray = arr => {
   const map = {};
   const group = [];
   for(let i = 0; i < arr.length; i++){
      if(typeof map[arr[i]] === 'number'){
         group[map[arr[i]]].push(arr[i]);
      }else{
         //the push method returns the new length of array
         //and the index of newly pushed element is length-1
         map[arr[i]] = group.push([arr[i]])-1;
      }
   };
   return group;
}
console.log(groupArray(arr));

Output

The output in the console will be −

[ [ 234, 234 ], [ 65, 65 ], [ 2, 2 ] ]
Updated on: 2020-10-20T11:49:38+05:30

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