Asp.net frontend and backend function variable mutual access

1. How to access the C # function in JavaScript?

2. How to access the C # variable in JavaScript?

3. How to access existing JavaScript variables in C?

4. How to access JavaScript Functions in C?

The answer to question 1 is as follows:

Execute functions in C # code in javaScript Functions:

Method 1:

1. Create a button to write the called or processed content to button_click in the background;

2. Write a js function on the front-end with the content document. getElementById ("btn1"). click ();

3. Call js functions on the frontend or backend to stimulate the click event, which is equivalent to accessing the c # function in the background;

Method 2:

1. function declaration as public background code (change public to protected) public string ss () {return ("");}

2. You can use <% = fucntion () %> in html to call the foreground script <script language = javascript> var a = "<% = ss () %> "; alert (a); </script>

Method 3:

1. <script language = "javascript">

<! -- Function _ doPostBack (eventTarget, eventArgument) {var theForm = document. form1; // indicates the form theForm of runat = server. _ EVENTTARGET. value = eventTarget; theFrom. _ EVENTARGUMENT. value = eventArgument; theForm. submit () ;}->

</Script>

<Input id = "Button1" type = "button" name = "Button1" value = "button" onclick = "javascript :__ doPostBack ('button1','') ">

When An ASPX page contains an asp: LinkButton or a server control with the AutoPostBack attribute and its value is true, ASP. NET automatically generates the following script for the page:

<Input type = "hidden" name = "_ EVENTTARGET" id = "_ EVENTTARGET" value = ""/>

<Input type = "hidden" name = "_ EVENTARGUMENT" id = "_ EVENTARGUMENT" value = ""/>

The two parameters are saved by the hidden form fields _ EVENTTARGET and _ EVENTARGUMENT.

The two hidden forms can be used to find the control ID and parameters causing page delivery:

String target = Request. Params ["_ EVENTTARGET"];

String args = Request. Params ["_ EVENTARGUMENT"];

Asp: Button and asp: ImageButton do not use _ doPostBack to send back pages. Therefore, the above Code is invalid when the two controls are used to send back pages.

Method 4:

<Script language = "javascript">

Function SubmitKeyClick ()

{If (event. keyCode = 13)

{Event. cancelBubble = true; event. returnValue = false; document. all. funName. value = "Name of the function you want to call"; document. form [0]. submit ();}}

</Script>

<INPUT onkeypress = "SubmitKeyClick ()" id = "aaa" type = "text">

<Input type = "hidden" name = "FunName">

<〈! -- Used to store the function you want to call-> -〉

In. CS, there are:

Public Page_OnLoad ()

{If (! Page. IsPost ())

{String strFunName = Request. Form ["FunName"]! = Null? Request. Form ["FunName"]: "";

// Determine which function to call based on the value returned

Switch (strFunName) {case "enter ()": enter ();

// Call the break function;

Case "other": // call other functions

Break;

Default: // call the default function break ;}}}

Public void enter ()

{//...... For example, calculating a value}

Question 2. How to access the C # variable in JavaScript?

The answer is as follows:

Method 1:

1. Access <input id = "xx" type = "hidden" runat = "server">

Method 2:

1. If the backend defines public string n, the format of the variable referenced in front-end js is '<% = n %>' or "+ <% = n %> +"

Method 3:

1. You can register a script "<script language = 'javascript '> var temp =" + tmp + "</script>" tmp is background variable,

Then, you can directly access temp in js to obtain the value.

3. How to access existing JavaScript variables in C? The answer is as follows:

Method 1:

1. the foreground uses static text controls to hide fields and write js variable values into them;

2. the backend uses request ["id"] to obtain the value;

Method 2: cookie or session can be used

4. How to access JavaScript Functions in C? The answer is as follows:

C # execute javaScript Functions in the Code:

Method 1: 1. Page. RegisterStartupScript ("ggg", "<script> SetVisible (1); </script> ");

Method 2: Use the Literal class and

Private void Button2_Click (object sender, System. EventArgs e)

{String str; str = "<script language = 'javascript '>"; str + = "selectRange ()"; str + = "</script> "; // Literal1.Visible = true; Literal1.Text = str ;}