CODEWITHSUNDEEP
javascriptasp.net
DanO
DanO

Reputation: 417

Passing a field to javascript and evaluate

I have a web form with several text boxes. I want to evaluate the default value in a text box and when user clicks on the field I want to clear it out. This is helping to reduce space on a form.

The below gives error message "Microsoft JScript Runtime error: object required.

Javascript:

function validateKeyword(f, flg, val) {
    switch (flg) {
        case 0: if (document.getElementById(f).value == val) { document.getElementById(f).value = ''; } break;
        case 1: if (document.getElementById(f).value == '') { document.getElementById(f).value = val; } break;
    }
}

ASP.NET textbox:

<asp:TextBox maxlength="150"  runat="server" name="First_Name" value="First Name" class="frmsel2" onfocus="javascript:validateKeyword('first_name',0,'First Name');" onblur="javascript: validateKeyword('first_name',1,'First Name');" alt="First Name" title="First Name" id="first_name"></asp:TextBox>

Upvotes: 0

Views: 89

Answers (3)

DanO
DanO

Reputation: 417

I ended up putting this in the Page_Load event in the code behind. (Made edits to use constant values). 

public partial class _Default : System.Web.UI.Page
{
    private const string FormDefaFirstName = "First Name";
    private const string FormDefaLastName = "Last Name";

  protected void Page_Load(object sender, EventArgs e)
  {
        first_name.Attributes.Add("onfocus", "javascript: if(this.value=='" + FormDefaFirstName + "') this.value='';");
        first_name.Attributes.Add("onfocusout", "javascript: if(this.value=='') this.value='" + FormDefaFirstName + "';");
        last_name.Attributes.Add("onfocus", "javascript: if(this.value=='" + FormDefaLastName + "') this.value='';");
        last_name.Attributes.Add("onfocusout", "javascript: if(this.value=='') this.value='" + FormDefaLastName + "';");


    if (!Page.IsPostBack)
    {
        first_name.Text = "First Name";
        last_name.Text = "Last Name";
    }
 }

Upvotes: 0

Hrant Muradyan
Hrant Muradyan

Reputation: 121

If you are using HTML5 I think you can use placeholder.

http://www.w3schools.com/html5/att_input_placeholder.asp

Upvotes: 1

kolin
kolin

Reputation: 2344

reference your ID in javascript by using 

document.getElementById(<%= first_name.ClientID %>).value = ''

Upvotes: 0

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