Considerations for Javascript Form Verification _ javascript tips-js tutorial

JavaScript can be used to verify the input data in the HTML form before the data is sent to the server. The typical form data verified by JavaScript includes: Are required items in the Form filled by the user? Is the email address entered by the user valid? Have you entered a valid date? Does the user input text in the data field (numericfield? Javascript form programming:

I. How to search form elements:

1. var oForm = document. getElementById ("Form1 ");

2. var oForm = document. forms [Form1] // search by name;

Ii. Common Features of form fields:

Disabled: Indicates whether a form control is available;

Form attribute: This attribute returns a form containing fields;

Blur (): This method causes the form field to lose focus;

Focus (): This method leads to focus for form fields;

Blur event: This event occurs when the form field loses focus, and then the onblur event handler is executed;

Focus event: This event occurs when the form field gets the focus, and then the onfocus event handler is executed;

Iii. Form submission, reset

Sumbit: oForm sumbit ();

Reset: oForm reset ();

4. Get the value of the text box:

Length otext. value. length;

5. Add element nodes, text nodes, and delete Elements

CreatElement, creatTextNode, remove;

6. select

7. Form Verification best practices:

Must be helpful to users;

Don't be annoying;

If possible, use the HTML function instead of Javascript.

All errors are displayed at one time;

Capture errors earlier;

If you are not sure, do not be too strict;