TypeScript: how to add multiple elements to an array of the same values-CodePudding

I would like to add multiple elements that all have the same value to an array of objects Something like '.push()' but with a count. I know I can do array.push(a, b, c), but I want to be able to do something like:

person {
firstName: string;
lastName: string;
age: number;
}

people: Person[];
numberPeople: number;

// some calculation to generate numberPeople, example: 23

person.push( {firstName: '', lastName: 'Smith', age: 0}, NumberPeople)

I know I can use a loop structure (for (i=0; i<NumberPeople;i ) person.push) but that gets cumbersome. Is there an easier way? I'm relatively new to JavaScript and TypeScript.

I've tried .fill() but that doesn't let me specify values.

thanks,

I know I can create my own function ( mpush(obj, count) ) but I would rather use something more elegant and standard, if there is something.

CodePudding user response：

You can use the inbuilt fill() method by first creating an Array of the right size and then populating it with a value multiple times.

interface person {
  firstName: string;
  lastName: string;
  age: number;
}

const samplePerson = {firstName: '', lastName: 'Smith', age: 0}

const people = Array(numberPeople).fill(samplePerson)

CodePudding user response：

You can use fill and here is an example using TypeScript.

type Person = {
    firstName: string;
    lastName: string;
    age: number;
}

let people: Person[]=[];

// you can replace 10 with the calculation 
let numberPeople: number = 10;  

// this will create an array with all elments having {firstName: '', lastName: 'Smith', age: 0}) as values, with length of numberPeople
people = Array(numberPeople).fill({firstName: '', lastName: 'Smith', age: 0})

CodePudding user response：

I would count the additions live, as I am adding more people.

Granted it is a zero based array, so 1st would be 0, the index in the array.

let people = [];

let samples = 23;

for (let i = 0; i < samples; i  )
{
    let person = { firstName: 'Bob_' i, lastName: 'Smith', age: 0 };

    people.push( { index: people.length, person } );
}

// We should now have the 23 people needed.
console.log(people.length); // 23

// Example of the first added.
console.log(people[0]);

/* Results:
  {
    "index": 0, 
    "person": {
      "firstName": "Bob_0",
      "lastName": "Smith",
      "age": 0
    }
  }
*/

CodePudding user response：

You can use .fill() indeed:

const NumberPeople = 3;
const people = Array(NumberPeople).fill({firstName: '', lastName: 'Smith', age: 0});

console.log(people);

// notice the above method places the same person in all positions
console.log(people[2].age); // will log 0
people[1].age = 4;
console.log(people[2].age); // will log 4

//
//
// if all values being the same object is a problem, you can use .map:

const people2 = [...Array(NumberPeople)].map(_ => ({firstName: '', lastName: 'Smith', age: 0}));

console.log(people2);
console.log(people2[2].age); // will log 0
people2[1].age = 4;
console.log(people2[2].age); // will log 0