How to return an array with the first 2 elements in an object and iterate until the end-CodePudding

I just want to return an array containing the first and second objects of the element.

The next 2 elements will be repeated after traversing the keys

Given the following object:

const object = {
  a: [
    { name: "John", age: 32 },
    { name: "David", age: 23 },
    { name: "Justin", age: 28 },
    { name: "Arnauld", age: 35 }
  ],
  b: [
    { name: "Ivan", age: 18 },
    { name: "Nekko", age: 13 },
    { name: "Lena", age: 25 }
  ],
  c: [
    { name: "Ann", age: 19 },
    { name: "Nick", age: 14 }
  ]
};

the result I want is

[
  { name: "John", age: 32 },
  { name: "David", age: 23 },
  { name: "Ivan", age: 18 },
  { name: "Nekko", age: 13 },
  { name: "Ann", age: 19 },
  { name: "Nick", age: 14 },
  { name: "Justin", age: 28 },
  { name: "Arnauld", age: 35 },
  { name: "Lena", age: 25 }
]

CodePudding user response：

You can use Object.values() and then you can use array.reduce() to get desire values.

const object = {
   a: [
     { name: "John", age: 32 },
     { name: "David", age: 23 },
     { name: "Justin", age: 28 },
     { name: "Arnauld", age: 35 }
   ],
   b: [
     { name: "Ivan", age: 18 },
     { name: "Nekko", age: 13 },
     { name: "Lena", age: 25 }
   ],
   c: [
     { name: "Ann", age: 19 },
     { name: "Nick", age: 14 }
   ]
};

let newArray = Object.values(object).reduce((prev, current) => ([...prev, ...current.slice(0,2)]),[]);
console.log(newArray)

CodePudding user response：

const object = {
  a: [
    { name: "John", age: 32 },
    { name: "David", age: 23 },
    { name: "Justin", age: 28 },
    { name: "Arnauld", age: 35 }
  ],
  b: [
    { name: "Ivan", age: 18 },
    { name: "Nekko", age: 13 },
    { name: "Lena", age: 25 }
  ],
  c: [
    { name: "Ann", age: 19 },
    { name: "Nick", age: 14 }
  ]
};

const result = Object.values(object).reduce((acc, cur) => {
  const arr = cur.map((item, index) => {
    return { ...item, index: Math.floor(index / 2) };
  });
    
  return [...acc, ...arr];
}, []).sort((a,b) => a.index - b.index);

console.log(result);

.as-console-wrapper { max-height: 100% !important; top: 0 }

this gives exact the order as you requested it.

EDIT

Explanation:

The solution iterates over Object.values() array and uses .reduce() in order to first assign an index to each element (in the arrays corresponding to keys a, b, c.

Then, it uses .sort() to obtain the desired order in the resulting array.

CodePudding user response：

const names = [];
while (true) {
    let test = false;
    for (const [key, value] of Object.entries(object)) {
        if (value.length > 0) {
            const arrays = value.splice(0, 2)
            names.push(...arrays)
            test = true
        }
    }
    if (test === false) break;
}
console.log(names);

i think something like this will do, but be careful using splice because it'll delete the values from the array