How to get the number of occurrences of each letter in specified string in JavaScript ?

How to get the number of occurrences of each letter in specified string in JavaScript ?Given a string, our task is finding the occurrence of a character in the string with the help of user-defined function.Example:
Input : “hello”
Output : h occur 1 times
e ocuur 1 times
l occur 2 times
o occur 1 times
Explanation : here “hello” have 1 h, so it have 1 value.
as same e have 1, l have 2 , o have 1.
Example 2:
Input : “did”
Output: d occur 2 times
i occur 1 timesApproach 1: In this approach we use a map data structure to store the number of times characters occur.First we initialize map with key each character of string and value for each is 0.We iterate over string and increment value of the character.Finally, print key-values of the map.Example:Javascript  function printans( ans ){  for( let [ key ,value] of ans)  {        console.log(`${key}  ocuurs  ${value} times` );          }  }  function count( str , outp_map ){  for( let i = 0 ;i < str.length ;i++)  {       let k = outp_map.get(str[i]);    outp_map.set(str[i], k+1) ;                  }    printans(outp_map);}  function count_occurs( test , callback ){    if( test.length === 0 )  {    console.log(" empty string ");    return ;  }  else  {         let ans = new Map();    for( let i = 0 ;i < test.length;i++)    {      ans.set(test[i], 0);    }          callback( test ,ans);        }  }  let test =  "helloworld";count_occurs( test ,count);  Output:h ocuurs 1 times e ocuurs 1 times l ocuurs 3 times o ocuurs 2 times w ocuurs 1 times r ocuurs 1 times d ocuurs 1 timesApproach 2: In this approach, we use nested for loop to iterate over string and count for each character in the string.First initialize count with value 0 for ith value of string.Now we iterate over string if ith value matches with the character, increase the count value by 1.Finally, print the value of count.Example:Javascript  function count_occur( str ){    if( str.length == 0 )  {    console.log("Invalid string")    return;  }    for( let i = 0 ;i < str.length ;i++)  {         let count = 0;    for( let j = 0 ;j < str.length ;j++)    {      if( str[i] == str[j] && i > j  )      {       break;      }      if( str[i] == str[j]  )      {        count++;      }    }    if( count > 0)    console.log(`${str[i]} occurs ${count} times`);        }  }  let test_str = “gfghello”;count_occur( test_str);Output:g occurs 2 times
f occurs 1 times
h occurs 1 times
e occurs 1 times
l occurs 2 times
o occurs 1 times