Narendra,

I tried below onChange script, it worked,

function onChange(control, oldValue, newValue, isLoading) {

if(isLoading || newValue == ''){

return;

}
var pattern = /^\(\d{3}\)\s\d{3}-\d{4}$/; //(xxx) xxx-xxxx

var phone = g_form.getValue('emer_contact');

if(!pattern.test(phone)){

phone = phone.replace(/\D/g,'');

var regex = /^\d{10}$/;

var is_valid = regex.test(phone);

if(!is_valid){

g_form.addInfoMessage('Invalid phone number. Please enter 10 digits');

g_form.clearValue('emer_contact');

}else{

phone = '(' + phone.slice(0,3) + ') ' + phone.slice(3,6)+'-' + phone.slice(6,10);

g_form.setValue('emer_contact', phone);

}

}

}