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Learning TypeScript 2.x - Second Edition
book

Learning TypeScript 2.x - Second Edition

by Remo H. Jansen
April 2018
Beginner content levelBeginner
536 pages
13h 21m
English
Packt Publishing
Content preview from Learning TypeScript 2.x - Second Edition

Interfaces

In TypeScript, we can use interfaces to ensure that a class follows a particular specification:

interface LoggerInterface{ 
    log(arg: any): void; 
} 
 
class Logger implements LoggerInterface { 
    log (arg: any){ 
        if (typeof console.log === "function") { 
            console.log(arg); 
        } else { 
            console.log(arg); 
        } 
    } 
} 

In the preceding example, we have defined an interface LoggerInterface and a class Logger, which implements it. TypeScript will also allow you to use interfaces to declare the type of an object. This can help us to prevent many potential issues, especially when working with object literals:

interface UserInterface { 
    name: string; 
    password: string; 
} 
 
// Error property password is missing 
let user: UserInterface = { 
    name: "" 
}; 
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Publisher Resources

ISBN: 9781788391474Supplemental Content