let arr = ['tea', 'pizza', 'tea', 'pizza', 'tea', 'milk'];
let res = {};

arr.forEach((item, index) => {
  let count = 0 ;
  const resValues = Object.keys(res);
    if(!resValues.includes(item)) {
       for(i=index; i<arr.length; i++) {
          if(arr[index] === arr[i]) {
            count++;
          }
        }
      const keyVal = arr[index];
      const value = count;
        res = {
          ...res,
          [keyVal] : value
        };
       }
});
const sortable = Object.entries(res);
sortable.sort(function(a, b) {
    return a[1] - b[1];
});
console.log(sortable);