Textbox value in javascript

Question

I have this textbox that has the limit in DB for input 255. And I am trying to built a function in JS that stops the user for inserting more than 255 characters in that textbox.

Here is the asp.net code:

<asp:TextBox Id="textbox" TextMode="MultiLine"
             oninput="F(id,this.value.length, 255)"
             runat="server" Columns="25" Rows="5"></asp:TextBox>

And here is the code in JS(just a test):

this.textCounter = function (ref,value, maxlimit) {
    if (value > maxlimit) {
        $('#textbox').value=" ";
    }
    return true;
}

Somehow the $('#textbox').value is undefined. What I can do?

If you are using jQuery then it has method val for getting/setting value i.e. $('#textbox').val("aaaa"); for setting and $('#textbox').val(); for getting. value is a property in javascript and your are using jQuery object thus your code was not working. — guleria
– guleria, Commented Jan 9, 2017 at 11:00

Khawaja Asim · Accepted Answer · 2017-01-09 11:52:10Z

2

You can use maxlength HTML property in your asp.net control. and that will work fine.

maxlength="255"

Edit:

<asp:TextBox Id="textbox" onKeyPress="return(this.value.length < 255);" runat="server" TextMode="MultiLine" Columns="25" Rows="5"></asp:TextBox>

edited Jan 9, 2017 at 11:52

answered Jan 9, 2017 at 10:58

Khawaja Asim

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4 Comments

Khawaja Asim Over a year ago

@GeorgeGreat can you please paste the full code with MaxLength propety ?

George Great Over a year ago

This one? public virtual int MaxLength { set; get; } Member of System.Web.UI.WebControls.TextBox

Khawaja Asim Over a year ago

<asp:TextBox Id="textbox" TextMode="MultiLine" MaxLength="255" runat="server" Columns="25" Rows="5"></asp:TextBox>

Khawaja Asim Over a year ago

@GeorgeGreat i have edited my answer and tested it my self, please have a look. with onKeyPress="return(this.value.length < 255);

Sigert Goeminne · Accepted Answer · 2017-01-09 10:55:08Z

1

You should use $('#textbox').html instead of $('#textbox').value. $('#textbox').html takes the content between the textbox tags. Because a textbox does not has a value attribute.

answered Jan 9, 2017 at 10:55

Sigert Goeminne

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Comments

VDWWD · Accepted Answer · 2017-01-09 12:01:47Z

1

You need to use

$("#<%= textbox.ClientID %>").val("myValue")

aspnet renames the textbox ID's to make sure there are no duplicates on the client side, so textbox can become something like PlaceHolder1_textbox. And then your hardcoded javscript reference will not work anymore.

edited Jan 9, 2017 at 12:01

answered Jan 9, 2017 at 10:56

VDWWD

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2 Comments

George Great Over a year ago

It says that the syntax is wrong. I must put as well ClientID="static"?

VDWWD Over a year ago

Using ClientIDMode="Static" is not recommended. It can lead to duplicate id's.

Enrico · Accepted Answer · 2017-01-09 12:25:35Z

-1

When you define your text your have to specified ClientIDMode="Static". In this way .NET create a input box with your name. Usually an input box name is more complex than the name you chose.

Another way is to use a bit of code in the javascript. Instead of $('#textbox') you have to use

$('#<%= yourtextbox.CliendId%>')

edited Jan 9, 2017 at 12:25

answered Jan 9, 2017 at 10:57

Enrico

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2 Comments

VDWWD Over a year ago

At least make sure the code is correct... $('#<%= yourtextbox.ClientID %>')

Enrico Over a year ago

Yes. You have to use it in an ASP.NET page

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