To understand the above code, you need some knowledge of network programming. Please refer to the introduction of form tag, select tag, input tag and onClick event on w3shool.

To put it simply, the above code does the following things:

The entire code defines a form, named form1, which is used to transmit data to the server, followed by input tags and The select tag is used to define the passed data

An input tag and onClick event onClick='swapCalendar(document.all("Pu00011_Input.trade_date"))' are used to set the date to be queried, Pu00011_Input.trade_date.

A select tag is used to select the query variety Pu00011_Input.variety

An input tag is used to set the market type Pu00011_Input.trade_type. From the code, the value of Pu00011_Input.trade_type is It is always 0, representing the futures market; from the commented out part of the code below, we can see that when Pu00011_Input.trade_type is 0, it represents the options market. It is estimated that the website has not implemented this function yet

Then there are three rows Input tags with button attributes, so they are in the form of buttons, and all have onClick attributes. When the button is pressed, the javascript script will be triggered, and the script will set the value of the action, such as the "Download text format" button, press it The action value will be set to Pu00012_download

form to pass data to the server, which is actually equivalent to passing parameters using a url address. For example, select December 6, 2012 as the date, select "Bean One" as the variety, and click "Download text format".