The front-end management program of the shopping cart --- only interacts with the server once (2. javascript part)

Cart. js
Save it as cart. js and put it in the same directory as the previous html.
//------------------------------------------------------------------------------
//
// File name: cart. js
//
// Description: Use the javascript function library at the front end of the shopping cart.
//
// Function list: On_Cancel (txtAmount, txtSum) ---- cancel this item
// On_Update () ---- update quantity
// On_Del () ---- delete all
// UpdateDate () ---- update form Display
// Round () ---- rounding the number of specified decimal places
//
// Aurthor: LiuYunpeng
//
// Date: 2000/09/03
//
// History: 2000/09/03 version 1.0
//
//------------------------------------------------------------------------------
// ---------------- Code begin here ------------------------------------------
Function On_Cancel (txtAmount, txtSum)
    {
TxtAmount. value = 0;
TxtSum. value = 0;
UpdateData ();
    }
// Update the form Display
Function UpdateData ()