Factory function syntax in typescript

Question

I don't understand the c type marker syntax here : https://visualstudiomagazine.com/blogs/tool-tracker/2015/12/factory-functions-typescript.aspx

function CreateCustomer<c extends ICustomer>(cust:{new(): c;}, 
                                         name: string, age: number): c

Can someone explain what is c above in the 3 different places ?

Answer 1

1st c is declaration that collection variable have to extend ICustomer (in app you can have VIPCustomer, MegaCustomer...)

Then 2nd c is just safetyguard that constructor of c is 100% extending ICustomer (returning this object into cust)

The last c is return type of the whole function.

Have a nice day!

Answer 2

1. <c extends ICustomer> means " c is a type that extends ICustomer "
2. cust:{new(): c;} means " cust is a function that can be called with new cust() and will return an object of type c "
3. function CreateCustomer/*...*/(/*...*/): c means "function CreateCustomer returns an object of type c "

The function can be called like that:
var john:Customer = CreateCustomer(Customer, "John", 35)
Where Customer is a class extending ICustomer interface.