group array and get count

Question

Say I have array like this:

[
   \"foo\",
   \"bar\",
   \"foo\"
   \"bar\",
   \"bar\",
   \"bar\",
   \"zoom\"
]

I want to group it so I

Answer 1

You could use the reduce() method which is avalible on the array object to achieve this grouping. So, something along the lines of this might achieve what you're after:

    var input = [
       "foo",
       "bar",
       "foo",
       "bar",
       "bar",
       "bar",
       "zoom"
    ]
    
    // Iterate the input list and construct a grouping via a "reducer"
    var output = input.reduce(function(grouping, item) {
    
      // If the current list item does not yet exist in grouping, set 
      // it's initial count to 1
      if( grouping[item] === undefined ) {    
        grouping[item] = 1;
      }
      // If current list item does exist in grouping, increment the 
      // count
      else {
        grouping[item] ++;
      }
    
      return grouping;
    
    }, {})
    
    console.log(output)