Iterate over an array of one type and copy only specific items in another array of another type

user_4424698 0
Viewed 86

In typescript, I have two arrays:

interface IFirst{
    name: string;
    age: number
}

interface ISecond {
    nickName: string;
    lastName: string;
}   

myFirstArray: IFirst[];
mySecondArray: ISecond[];

myFirstArray = [
    {name: 'tim', age: 20},
    {name: 'jim', age: 30}
]

How can I iterate through myFirstArray and set all names to nickNames in mySecondArray? Something like:

this.myFirstArray.forEach((element: IFirst) => {
        this.mySecondArray.push({nickName = element.name});
      })
angular typescript arrays
4 Answers

If you want to assign only nickname, then you need to make lastname as optional in ISecond interface like lastName?: string and interface will be,

interface ISecond {
  nickName: string;
  lastName?: string;
}

You can use this.myFirstArray.map() method and assign nickname value as myFirstArray element name to this.mySecondArray like,

this.mySecondArray = this.myFirstArray.map((element: IFirst) => {
  return { nickName: element.name };
});

console.log("this.mySecondArray ", this.mySecondArray);

Working code in Stackblitz... (Take a look at console)..

user_77853370

Here you have mySecondArray is of type array ISecond. So whenever you want to assign values in it you should assign both properties of the object.

Like below - 

this.myFirstArray.map((element: IFirst) => {
  this.mySecondArray.push({nickName = element.name, lastName: ''});
})
user_78438280

You can use map method:

this.myFirstArray = [
    {name: 'tim', age: 20},
    {name: 'jim', age: 30}
];
this.mySecondArray = this.myFirstArray.map(({name, age})=> <ISecond><any>{ 
    nickname: name,
    lastName: ''
    });
console.log(this.mySecondArray);
user_16462400

You should initialize second array:

mySecondArray: ISecond[] = [];

and then push elements:

this.myFirstArray.forEach((element: IFirst) => {
    this.mySecondArray.push({nickName: element.name, lastName: ''});
})
user_67130460
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