JavaScript provides a special keyword, “this”, which is a reference to the object that contains a JavaScript statement or function call. For example, if we have a text box object, we can pass a reference for that object to a function with the statement:

The doSomethingTo function could then accept the text box reference into a parameter, as in:

 function doSomethingTo(myfield) {. .}

Now doSomethingTo can refer to the text box within the function using myfield; as in the statement myfield.focus, for instance.