How to Group Array Items into Objects in JavaScript?

Grouping Array Items into Objects

You're tasked with transforming an array of objects into a new array with grouped objects, where the values for each group are combined into an array. Here's how you can approach this problem:

var myArray = [
  {group: "one", color: "red"},
  {group: "two", color: "blue"},
  {group: "one", color: "green"},
  {group: "one", color: "black"}
];

// Create a mapping of group names to arrays of values
var group_to_values = myArray.reduce(function (obj, item) {
  obj[item.group] = obj[item.group] || [];
  obj[item.group].push(item.color);
  return obj;
}, {});

// Convert the mapping to an array of grouped objects
var groups = Object.keys(group_to_values).map(function (key) {
  return {group: key, color: group_to_values[key]};
});

The resulting groups array will be:

[
  {group: "one", color: ["red", "green", "black"]},
  {group: "two", color: ["blue"]}
]

This approach utilizes the reduce and map array methods to efficiently group and transform the data.

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