Write a function “groupBy(array, callback)”

Question

I have a JavaScript task where I have to implement a function \"groupBy\", which, when given an array of objects and a function, returns an object w

Answer 1

Here is another approach using reduce:

 var list = [{
     id: "102",
     name: "Alice"
   },
   {
     id: "205",
     name: "Bob",
     title: "Dr."
   },
   {
     id: "592",
     name: "Clyde",
     age: 32
   }
 ];



 function groupBy(list, callback) {
   return list.reduce((acc, x) => {
     const key = callback(x);
     if (!acc[key]) {
       return {
         ...acc,
         [key]: [x]
       }
     }
     return {
       ...acc,
       [key]: [...acc[key], x]
     }

   }, {})
 }

// callback functions
 function nameLength(obj) {
   return obj.name.length;
 }

 function objectProperty(obj) {
   return obj.id
 }


 console.log('group by name length:', groupBy(list, nameLength));
 console.log('group by Id:', groupBy(list, objectProperty));