Extending the functionality of the JavaScript base object in Typescript

In recent work, take note: Suppose we need a function, the output of a number such as 10000 to the following string format "10,000", generally write a method, then I would like to more convenient, directly add a format method to the # type, For example, a method called Toformat to implement a formatted string.

Add a. D.ts definition

The method to extend a base object in typescript requires that the compiler have this method in advance:

1 interface Number {2    Toformat (): string; 3 }

Add implementation

The specific implementation can be written as needed, and it is important to note that the prototype object is added to the line:

1Number.property.toFormat =function () {2     //get the value of the number, i.e. the number itself3     varValue = This. ValueOf ();4     //here is the specific handling code, which is skipped here5     varstr = "Code";6     //return and then7     returnstr;8}

You can call it directly:

1 var i = 10000; 2 Console.log (I.toformat ());

My implementation here is written in JavaScript, and if it is in typescript, it can be written using TS.

Extending the functionality of the JavaScript base object in Typescript