how to pass textbox id as a parameter to the function in javascrip

Question

1.00/5 (1 vote)

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hi
I have written a javascript function for validation of numbers in asp.net
I want to use same function to be called on 4 textboxes.

JavaScript

<script type="text/javascript"  language="javascript">
    function Isnumber(txt)   
    {
    var validcharacter="0123456789.";
    var char1;

   var textbox= document.getElementById("txt");
   

    var stext= textbox.value;
    for(i=0; i<=stext.length;i++)
    {
    
    char1= stext.charAt(i);
    
    if(validcharacter.indexOf(char1)==-1 )
    {
    
     alert("please enter only numbers");
     document.getElementById("txt").value="";
     return false;
    }
     
    }
    
    }

ASP.NET

<asp:TextBox ID="txtHRA"  runat="server"
önKeyPress="javascript:Isnumber('<%= txtHRA.ClientID%>')"/>

its not working

txt is the function not able to get textbox id which i have passed while calling function.
I have to use the same function for multiple textbox how can i pass texbox id to the function in javascript

Posted 25-Sep-12 17:04pm

Amu@184

Updated 26-Sep-12 13:37pm

Sergey Alexandrovich Kryukov

v3

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Comments

Sergey Alexandrovich Kryukov 25-Sep-12 23:12pm

Why passing the id?
--SA

Amu@184 27-Sep-12 6:13am

Thanks. Its Working. you are right.
I m learning java script.

6 solutions

Solution 3

// Javascript function

JavaScript

function fnAllowDigitsOnly(key)
{      
    var keycode=(key.keywhich)?key.which:key.keyCode;
    if(keycode<48||keycode>57 || keycode !=8)
    {
        return false;
    }
}

// .cs code for calling javascript function

C#

protected void Page_Load(object sender, EventArgs e)
{
    if (!IsPostBack)
    {
       // for each textbox u should call same function 
       text1.Attributes.Add("onkeypress", "return fnvalidatedigit(event)");
       text2.Attributes.Add("onkeypress", "return fnvalidatedigit(event)");
    }
}

Posted 25-Sep-12 18:21pm

solanki.net

Updated 26-Sep-12 14:58pm

v2

Solution 5

C#

function IsSpacial(txt)   {
           var char1;
           var stext = txt.value;
           keyCode = stext.charCodeAt(0);
           if (((keyCode >= '33') && (keyCode <= '47')) || ((keyCode >= '48') && (keyCode <= '57'))||((keyCode >= '58') && (keyCode <= '64')) || ((keyCode >= '91') && (keyCode <= '96')) || ((keyCode >= '123') && (keyCode <= '183'))) {
               alert("First letter is start with  character in Provider Name.");
          return false;
        }
        else {
            return true;
        }


   }

<asp:textbox id="txt1" runat="server" skinid="TextBoxMandatory" maxlength="50" onkeyup="IsSpacial(this)" xmlns:asp="#unknown">

Posted 20-May-13 0:32am

Member 7893125

Updated 20-May-13 0:34am

v2

Solution 6

#Your code is perfect, just remove double cotes while getting the id:
'''
var textbox= document.getElementById("txt");

change to:

var textbox= document.getElementById(txt);

and call the method as:

önKeyPress="javascript:Isnumber(this.id)"
'''

##One thing: you are calling the method onkeypress which will not check the current input charcter, it will take the previous values like if i have 1234 in the text box and now if i press 5 then the script will calling textbox.value it will take only 1234.

Posted 22-Jun-15 18:22pm

vj.negi08

Updated 22-Jun-15 18:30pm

v3

Comments

Dave Kreskowiak 23-Jun-15 0:37am

You realize this is a 3 years question right?

Don't reply to them.

Solution 4

XML

<asp:TextBox ID="txtHRA" runat="server"

onKeyPress="javascript:Isnumber(this.id);"/>

or simply use

XML

<asp:TextBox ID="txtHRA" runat="server"

onKeyPress="javascript:Isnumber(this);"/>

by doing this you can directly get textbox object. So, no need to get object from id.

Posted 25-Sep-12 18:57pm

itskvini

v2

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Sergey Alexandrovich Kryukov · Accepted Answer · 2012-09-25T17:27:00

Probably, you started programming very recently, but the problem is: JavaScript is in fact very hard to understand, despite the simplicity of typical application code.

Instead of passing the id, you can pass the control object itself. Let me show a simple example, with HTML and JavaScript only:

XML

<html>
    <head>
        <script type="text/javascript">
            function doSomethingWithTextBox(textBox) {
                alert(textBox.value);
            }
        </script>
    </head>
<body>

<input type="text" onkeydown="doSomethingWithTextBox(this)" />
<p>Some other text box:</p>
<input type="text" onkeydown="doSomethingWithTextBox(this)" />

</body>
</html>

As you can see, the required parameter is passed as "this" in the event declaration.

[EDIT]

And when you have different text boxes, the same handler will still distinguish them, because "this" object instances are different.
Problem solved!

—SA

jkirkerx · Accepted Answer · 2012-09-25T18:08:00

on your webform control, it would be something like

attribute.add("onBlur="doSomethingWithTextBox(this); return false;)

Try Sergey's first, I use attribute, didn't know the control would accept javascript events. But wait, he's using a regular html element. so if your using a webcontrol, I think attributes would inject the attribute and do the job.