[TypeScript] Make Properties and Index Signatures Readonly in TypeScript

标签：evel   javascrip   only   against   orm   rate   var   use case   rip   

TypeScript 2.0 introduced the readonly modifier which can be added to a property or index signature declaration. It helps prevent against unintended property assignments. This lesson gives various use cases for readonly and shows what the generated JavaScript code looks like.

Normal use case for ‘readonly‘:

interface User {
   readonly id: nunber;  
   name: string
} 

class User {

  readonly id: number;
   name: string; 
  constructor(
      id: number, name: string
  ) {
      this.id = id;
      this.name = name;
  }
}

Make a array readonly:

const level: ReadonlyArray<string> = [
 ‘master‘,
 ‘beginner‘
];

[TypeScript] Make Properties and Index Signatures Readonly in TypeScript

标签：evel   javascrip   only   against   orm   rate   var   use case   rip   

原文地址：http://www.cnblogs.com/Answer1215/p/7811475.html