What should we name the type parameter?

Question

What should we name the type parameter?

After familiarizing myself with Typescript and understanding the concept of generic type T, I encountered an issue with a simple example. Can you pinpoint what's wrong?

function test1<string>(x:number):boolean{
    let s:string="hello";
    if (x==1 && s==="hello") return true
    else return false
}

The compiler is showing an error: "Type parameter name cannot be 'string'". The problem lies within <string>. In this code snippet, I'm attempting to define a non-generic type parameter, specifically for a <string>.

typescript

Answer 1

Answer №1

It is important to note that reserved keywords like String cannot be used as generic names. Instead, the extends keyword can be utilized to define a non-generic. Take a look at the example below:

interface Lengthwise {
    length: number;
}

function loggingIdentity<T extends Lengthwise>(arg: T): T {
    console.log(arg.length);  // This assures us that it has a .length property, eliminating any errors
    return arg;
}

For more information on generics, you can visit: https://www.typescriptlang.org/docs/handbook/generics.html

Answer 2

It is important to note that reserved keywords like String cannot be used as generic names. Instead, the extends keyword can be utilized to define a non-generic. Take a look at the example below:

interface Lengthwise {
    length: number;
}

function loggingIdentity<T extends Lengthwise>(arg: T): T {
    console.log(arg.length);  // This assures us that it has a .length property, eliminating any errors
    return arg;
}

For more information on generics, you can visit: https://www.typescriptlang.org/docs/handbook/generics.html

What should we name the type parameter?

Answer №1

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