Generic Fucntion:
For example we have a set of data and an function:
interface HasName { name: string; } const heros: HasName[] = [ {name: ‘Jno‘}, {name: ‘Miw‘}, {name: ‘Ggr‘}, {name: ‘Gew‘}, {name: ‘Wfe‘} ]; function cloneArray(ary: any[]): any[] { return ary.slice(0); } const clones = cloneArray(heros);
When we check the ‘clones‘ type, you can see it is ‘any[]‘.
To add more type information we can change the function:
function cloneArray<T>(ary: T[]): T[] { return ary.slice(0); }
Now we get ‘clones‘ type as ‘HasName[]‘.
Generic Class:
class SuperCharacter { constructor(public name: string) { } } class Hero extends SuperCharacter { } class SuperTeam { constructor(public members: SuperCharacter[], public leader: SuperCharacter ) { } } const captainAmerica = new Hero(‘Captain America‘); const thor = new Hero(‘Thor‘); const ironMan = new Hero(‘IronMan‘); const avengers = new SuperTeam( [captainAmerica, thor, ironMan], captainAmerica ); const members = avengers.members;
If we check ‘avengers‘ type is ‘SuperTeam‘. ‘memebers‘ type is ‘SuperCharacter[]‘.
To add more information to the types we can do:
class SuperTeam<T> { constructor(public members: T[], public leader: T ) { } }
Now the ‘avengers‘ type is ‘SuperTeam<Hero>‘ and ‘members‘ type is ‘Hero[]‘.
Now, let‘s say we have another class:
class Villain extends SuperCharacter { }
Have some members.
const luthor = new Villain(‘Luthor‘); const bizarro = new Villain(‘Bizarro‘); const captainCold = new Villain(‘Captain Cold‘); const megaCrossoverTeam = new SuperTeam([ captainAmerica, thor, ironMan, luthor, bizarro, captainCold ], captainAmerica);
‘megaCrossoverTeam‘ is type of ‘SuperTeam<Hero | Villain>‘.
If we want to add some restrictions to the class, we can do:
class SuperTeam<T extends SuperCharacter> { constructor(public members: T[], public leader: T ) { } }
Then the example below will throw error:
const avengers = new SuperTeam( [0, 1, 2], 0 );
Because the type is number.
