how to get index inside object on array to make it new obejct based on longest index-CodePudding

i have an array like this:

arrays = [
 {"y":"2020","OVO":3},
 {"y":"2021","OVO":2,"Dana":1},
 {"y":"2019","OVO":2,"Dana":1,"Shopepay":3},
 {"y":"2018","OVO":2,"Dana":1,"Shopepay":4,"Gopay":1}, //length = 5
 {"y":"2022","OVO":2,"Dana":1,"Shopepay":1}
];

now i want to create new array based on longest object key from arrays. should from this:

{"y":"2018","OVO":2,"Dana":1,"Shopepay":4,"Gopay":1}, //length = 5

to this :

['OVO','Dana','Shopepay','Gopay']

how to achieve that in javascript? thanks in advance.

CodePudding user response：

Looking for something like this?

const arrays = [
 {"y":"2020","OVO":3},
 {"y":"2021","OVO":2,"Dana":1},
 {"y":"2019","OVO":2,"Dana":1,"Shopepay":3},
 {"y":"2018","OVO":2,"Dana":1,"Shopepay":4,"Gopay":1},
 {"y":"2022","OVO":2,"Dana":1,"Shopepay":1}
];
const longestArray = arrays.sort((a, b) => Object.keys(a).length - Object.keys(b).length)?.pop(); // sort for most object with most properties

console.log(Object.keys(longestArray).slice(1)); // remove first element from array

Or as simple one-liner:

Object.keys(arrays.sort((a, b) => Object.keys(a).length - Object.keys(b).length)?.pop()).slice(1);

CodePudding user response：

Use .reduce() to achieve your goal

arrays = [
 {"y":"2020","OVO":3},
 {"y":"2021","OVO":2,"Dana":1},
 {"y":"2019","OVO":2,"Dana":1,"Shopepay":3},
 {"y":"2018","OVO":2,"Dana":1,"Shopepay":4,"Gopay":1}, //length = 5
 {"y":"2022","OVO":2,"Dana":1,"Shopepay":1}
];

const max = arrays.reduce((prev, current) => (prev.length > Object.keys(current).length) ? prev : Object.keys(current)).splice(1)

console.log(max)