Hi ,
You can use Regex for this.
In your form use Leave tag like below and use soapcall tag and specify new function which you will create in JavaScript file.
<leave>
<soapCall name="functionName" service ="">
<param exprIn="[give full path of field you want to check]" type="string"/>
</leave>
Make sure : In Javascript file , function you define have syntax like below
namespace_schema_fucntionName(test)
{
var res= test.match(); // Use regex here to find special character
if(res==null)
{
alert("special character found")
}
}
Thanks,
Kapil