JavaScript Action Form Instance Explains of

1. Get Form References

1 > Get it by direct positioning

document.getElementById();
document.getElementsByName();
document.getElementsByTagName();

2 > Get references through collections

document.forms[ subscript ]
document.forms["name"]
document.forms.name

3 > Get'(only applicable to forms) directly from name

document.name

2. Get references to form elements

1 > Direct acquisition

document.getElementById();
document.getElementsByName();
document.getElementsByTagName();

2 > Get by Collection

 form object .elements  Get a collection of all the elements in the form 
 form object .elements[ subscript ]
 form object .elements["name"]
 form object .elements.name

3 > Direct via name form

Form object. name

3. Common properties and methods of form elements

1 > Gets the value of a form element

Form Element Object. value Gets or sets a value

2 > attribute

disabled Gets or sets whether the form control disables true false
form Reference to Form Containing this Element

3 > Method

blur() Lost Focus
focus() Getting Focus