How can I approach and align elements in the array?

user_14929971 0
Viewed 216

I already tried:

let age = arr.sort(function(a, b) {
    return b -a;
});

it was good for simple array, but it does not work. In this array:

let list = [
  [
    ['firstName', 'Joe'],
    ['age', 42],
    ['gender', 'male'],
  ],
  [
    ['firstName', 'Mary'],
    ['lastName', 'Jenkins'],
    ['age', 36],
    ['gender', 'female'],
  ],
  [
    ['lastName', 'Kim'],
    ['age', 40],
    ['gender', 'female'],
  ],
];

it's double array, and 'age' index locate is different. How can I approach the 'age' and align? I want to sort ascending.

arrays javascript
4 Answers

You can use fromEntries to convert your array item into object and then sort. But you should consider updating the item to object to avoid this unnecessary conversion.

const list = [ [ ['firstName', 'Joe'], ['age', 42], ['gender', 'male'], ], [ ['firstName', 'Mary'], ['lastName', 'Jenkins'], ['age', 36], ['gender', 'female'], ], [ ['lastName', 'Kim'], ['age', 40], ['gender', 'female'], ], ];
list.sort((a, b) => Object.fromEntries(a).age - Object.fromEntries(b).age);

console.log(list);

user_47584940

You can do the following by finding the index of the child array where we can find age. From the example we can see that age is at index 0 and the age value is at index 1 of the sub array. You can than compare the age values.

 list = [
  [
    ['firstName', 'Joe'],
    ['age', 42],
    ['gender', 'male'],
  ],
  [
    ['firstName', 'Mary'],
    ['lastName', 'Jenkins'],
    ['age', 36],
    ['gender', 'female'],
  ],
  [
    ['lastName', 'Kim'],
    ['age', 40],
    ['gender', 'female'],
  ],
];

res = list.sort((a, b) => {
  ageIndexA = a.findIndex(item => item[0] ==='age');
  ageIndexB = b.findIndex(item => item[0] === 'age');
  return a[ageIndexA][1] - b[ageIndexB][1];
});

console.log(res);

user_29137230

The following should work:

let list = [
  [
    ['firstName', 'Joe'],
    ['age', 42],
    ['gender', 'male'],
  ],
  [
    ['firstName', 'Mary'],
    ['lastName', 'Jenkins'],
    ['age', 36],
    ['gender', 'female'],
  ],
  [
    ['lastName', 'Kim'],
    ['age', 40],
    ['gender', 'female'],
  ],
];
const compareFunction = (a,b) => {
  return a.age - b.age;
}
const sortList = (arr) => {
  const objectList = arr.map(e => Object.fromEntries(e));
  return objectList.sort(compareFunction);
}
console.log('sorted:', sortList(list));

user_146972090

The following will sort your array according to ascending age:

let list = [
  [
    ['firstName', 'Joe'],
    ['age', 42],
    ['gender', 'male'],
  ],
  [
    ['firstName', 'Mary'],
    ['lastName', 'Jenkins'],
    ['age', 36],
    ['gender', 'female'],
  ],
  [
    ['lastName', 'Kim'],
    ['age', 40],
    ['gender', 'female'],
  ],
];
let age = list.sort(function(a, b) {
    return a.filter(aa=>aa[0]=="age")[0][1] 
          -b.filter(bb=>bb[0]=="age")[0][1];})
    
console.log(age)

// this is a better approach:
let listo=list.map(e=>e.reduce((a,[k,v])=>(a[k]=v,a), {}));
console.log(listo.sort((a,b)=>a.age-b.age))

However, it would be better to store your data in a different format:. My second part generates such a format in listo. The sorting function is then trivial again ((a,b)=>a.age-b.age):

[
  {
    "firstName": "Mary",
    "lastName": "Jenkins",
    "age": 36,
    "gender": "female"
  },
  {
    "lastName": "Kim",
    "age": 40,
    "gender": "female"
  },
  {
    "firstName": "Joe",
    "age": 42,
    "gender": "male"
  }
]
``´
user_26100610
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