ContextQMD
Back to Content

Signature (functions)

files/en-us/glossary/signature/function/index.md

latest2.2 KB
Original Source

A function signature (or type signature, or method signature) defines input and output of {{Glossary("Function", "functions")}} or {{Glossary("Method", "methods")}}.

A signature can include:

  • {{Glossary("Parameter", "parameters")}} and their {{Glossary("Type", "types")}}
  • a return value and type
  • {{Glossary("Exception", "exceptions")}} that might be thrown or passed back
  • information about the availability of the method in an {{Glossary("OOP", "object-oriented")}} program (such as the keywords public, static, or prototype).

In depth

Signatures in JavaScript

{{Glossary("JavaScript")}} is a loosely typed or a dynamic language. That means you don't have to declare the type of a variable ahead of time. The type will get determined automatically while the program is being processed. A signature in JavaScript can still give you some information about the method:

js
MyObject.prototype.myFunction(value);
  • The method is installed on an {{Glossary("object")}} called MyObject.
  • The method is installed on the prototype of MyObject (thus it is an {{Glossary("Method", "instance method")}}) as opposed to being a {{Glossary("static method")}}.
  • The name of the method is myFunction.
  • The method accepts one parameter, which is called value and is not further defined.

Signatures in Java

In {{Glossary("Java")}}, signatures are used to identify methods and classes at the level of the virtual machine code. You have to declare types of variables in your code in order to be able to run the Java code. Java is strictly typed and will check any parameters at compilation time if they are correct.

java
public static void main(String[] args)
  • The public keyword is an access modifier and indicates that this method can be called by any object.
  • The static keyword indicates that this method is a class method as opposed to being an instance method.
  • The void keyword indicates that this method has no return value.
  • The name of the method is main.
  • The method accepts one parameter of type String Array. It is named args.

See also