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Book Overview & Buying
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Table Of Contents
Full-Stack React, TypeScript, and Node - Second Edition
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Generics allow a type definition to include an associated type that can be chosen by the user of the generic type, instead of being dictated by the type creator. In this way, there are structures and rules, but still some amount of flexibility. Generics will definitely come into play later when we code with React, so let’s learn about them here.Generics can be used for functions, classes, and interfaces. Let’s look at an example of generics with functions. Create a file called functionGeneric.ts and add the following code:
function getLength<T>(arg: T): number {
if(arg.hasOwnProperty("length")) {
return arg["length"];
}
return 0;
}
console.log(getLength<number>(22));
console.log(getLength("Hello world."));
Note that this code has errors, but we’ll work through those together. If we start at the top, we see a function called getLength<T>. This function uses a generic, <T>...