New upcoming array method called groupBy()
The groupBy() method is a forthcoming addition to the JavaScript Array object, currently positioned at Stage 3 within the TC39 process.
✅ Its advancement to Stage 3 indicates a high likelihood of being incorporated into the ECMAScript standard soon.
✅ groupBy() expects a callback function as its parameter.
✅ The callback function is invoked for each array element, and it should yield a string or symbol representing the group to which the element belongs.
Syntax
Object.groupBy(items, callbackFn)
Example #1
const result = Object.groupBy(inventory, ({ type }) => type);
Result is:
{
vegetables: [
{ name: 'asparagus', type: 'vegetables', quantity: 5 },
],
fruit: [
{ name: "bananas", type: "fruit", quantity: 0 },
{ name: "cherries", type: "fruit", quantity: 5 }
],
meat: [
{ name: "goat", type: "meat", quantity: 23 },
{ name: "fish", type: "meat", quantity: 22 }
]
}
Example #2
const number = [1, 2, 3, 4, 5, 6, 7, 8];
const groupBy = Object.groupBy(number, (num, index) => {
return num % 2 === 0 ? 'even' : 'odd'
})
console.log('groupBy', groupBy);
Result is:
{
"odd": [1, 3, 5, 7],
"even": [2, 4, 6, 8]
}