group by iteration plus group when repeating two fields in javascript-CodePudding

I have the following array:

[
{name:"jhon",surname:"connor",age:21},
{name:"jhonny",surname:"lator",age:22},
{name:"celia",surname:"mcgregor",age:23},
{name:"raul",surname:"fernandez",age:25},
{name:"marcela",surname:"fernandez",age:25},
{name:"omar",surname:"caster",age:26},
{name:"luna",surname:"potter",age:30},
{name:"harry",surname:"potter",age:30},
]

and I want to have the following order:

[
{order:1,name:"jhon",surname:"connor",age:21},
{order:2,name:"jhonny",surname:"lator",age:22},
{order:3,name:"celia",surname:"mcgregor",age:23},
{order:4,name:"raul",surname:"fernandez",age:25},
{order:4,name:"marcela",surname:"fernandez",age:25},
{order:5,name:"omar",surname:"caster",age:26},
{order:6,name:"luna",surname:"potter",age:30},
{order:6,name:"harry",surname:"potter",age:30},
]

If the last name and age are the same, don't count in the iteration of the order.

in javascript.

CodePudding user response：

Here you go (Added descriptive comments in the below code snippet) :

// Input array
const arr = [
  {name:"jhon",surname:"connor",age:21},
  {name:"jhonny",surname:"lator",age:22},
  {name:"celia",surname:"mcgregor",age:23},
  {name:"raul",surname:"fernandez",age:25},
  {name:"luna",surname:"potter",age:30},
  {name:"marcela",surname:"fernandez",age:25},
  {name:"omar",surname:"caster",age:26},
  {name:"harry",surname:"potter",age:30}
];

// For safer side, First sort the array in ascending order based on age property.
arr.sort((a, b) => a.age - b.age);

// Logic to add the order property in each object of arr.
const res = arr.map((obj, index) => {
  obj.order = index === 0 ? 1 : (arr[index - 1].surname === obj.surname && arr[index - 1].age === obj.age) ? arr[index - 1].order : arr[index - 1].order   1
  return obj;
});

// Output
console.log(res);

CodePudding user response：

I’d implement it like this

const array = [] // your array of objects
const newOrderedArr = array.map((obj, i) => {
if(i === 0) return { …obj, order: 1 };
return { …obj, order: (array[i - 1].surname === obj.surname && array[i - 1].age === obj.age)? array[i - 1].order : array[i - 1].order   1};
})

Assuming that you only check the previous object for similar surnames and ages