[Edit]

TypeScript - class methods overloading

1 contributors

2 contributions

0 discussions

7 points

Created by:

Mariam-Barron

811

In this article, we would like to show how to overload method in class in u>TypeScript.

TypeScript supports function overloading syntax that lets to deflate multiple functions with the same name, different arguments and return types. It is required just to provide some functions declarations and one function definition inside class.

Quick solution:

xxxxxxxxxx
 
class SomeClass {
​
    public someMethod(): ResultType;                          // <----- declaration
    public someMethod(a: ArgType1): ResultType;               // <----- declaration
    public someMethod(a: ArgType2, b: ArgType3): ResultType;  // <----- declaration
    // ...
​
    public someMethod(a?: any, b?: any): ResultType {         // <----- definition
        // ...                                                // <----- definition
    }                                                         // <----- definition
}
​
// ...

Practical example

Edit

xxxxxxxxxx
 
class Printer {
​
    public print(a: string): void;               // <----- declaration
    public print(a: string, b: string): void;    // <----- declaration
​
    public print(a: string, b?: string): void {  // <----- definition
        if (b) {                                 // <----- definition
            console.log(a + ' ' + b);            // <----- definition
        } else {                                 // <----- definition
            console.log(a);                      // <----- definition
        }                                        // <----- definition
    }                                            // <----- definition
}
​
const printer = new Printer();
​
printer.print('Hi!');
printer.print('Hi', 'John!');