display an alert box when an existing option is added to dropdown from a textbox

**shravanti88** · 03-20-2010, 04:23 AM

Hi,

I have a form that includes dropdown box, text box and add button.when a value is entered in the text box and the add button is clicked, it will added to the dropdown box. I need to create an alert message displaying "the value already exists" when an existing option is entered in the textbox.
The code i have created is as follows.Now i need to include a statement within the function to display an alert message.

[code]<html>
<script type= "text/javascript" language="javascript">
function addition()
{
var textb= document.getElementById("txtCombo");
var combo= document.getElementById("combo");
var option= document.createElement("option");
option.text= textb.value;
option.value= textb.value;
combo.add(option);
}
</script>
<body>
<form>
location <select name="combo" id="combo" >
<option>ooty
<option>kodai
<option>chennai
</select>
<input type="text" name="txtCombo" id="txtCombo">
<input type="button" value="add" onclick="addition()">
</form>
</body>
</html>[code]

Thanks,

Regards,
Shravs

**vwphillips** · 03-20-2010, 10:48 AM

Code:

<html>
<script type= "text/javascript" >
function addition(){
 var text= document.getElementById("txtCombo").value;
 var combo= document.getElementById("combo");
 if (!this.save){
  this.save=[''];
  for (var z0=0;z0<combo.options.length;z0++){
   this.save.push(combo.options[z0].value)
  }
 }
 if (text.replace(/\s/g,'')==''){
  alert('Blank');
  return;
 }
 for (var z0=0;z0<this.save.length;z0++){
  if (this.save[z0]==text){
   alert('Duplicate');
   return;
  }
 }
 this.save.push(text);
 var option= document.createElement("option");
 option.text= text;
 option.value= text;
 combo.add(option);
}
</script>
<body>
<form>
location <select name="combo" id="combo" >
<option>ooty
<option>kodai
<option>chennai
</select>
<input type="text" name="txtCombo" id="txtCombo">
<input type="button" value="add" onclick="addition()">
</form>
</form>
</body>
</html>

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