groupBy < Object < JavaScript

The Object groupBy() static method groups the elements of a given iterable according to the string values returned by a provided callback function.

    
    const inventory = [
      { name: "asparagus", type: "vegetables", quantity: 5 },
      { name: "goat", type: "meat", quantity: 23 },
      { name: "cherries", type: "fruit", quantity: 5 },
      { name: "fish", type: "meat", quantity: 22 },
    ];

    // group objects in array by one of the object's properties
    const inventoryGroupByType = Object.groupBy(inventory, ({ type }) => type);

    console.log(inventoryGroupByType)
    {
       "fruit":[
          {
             "name":"cherries",
             "quantity":5,
             "type":"fruit"
          }
       ],
       "meat":[
          {
             "name":"goat",
             "quantity":23,
             "type":"meat"
          },
          {
             "name":"fish",
             "quantity":22,
             "type":"meat"
          }
       ],
       "vegetables":[
          {
             "name":"asparagus",
             "quantity":5,
             "type":"vegetables"
          }
       ]
    }


    // another example
    function okOrRestock({ quantity }) {
      return quantity > 5 ? "ok" : "restock";
    }

    const inventoryGroupByRestock = Object.groupBy(inventory, okOrRestock);

    console.log(inventoryGroupByRestock)
    {
       "ok":[
          {
             "name":"goat",
             "quantity":23,
             "type":"meat"
          },
          {
             "name":"fish",
             "quantity":22,
             "type":"meat"
          }
       ],
       "restock":[
          {
             "name":"asparagus",
             "quantity":5,
             "type":"vegetables"
          },
          {
             "name":"cherries",
             "quantity":5,
             "type":"fruit"
          }
       ]
    }