How can I check whether a option already exist in select by Prototype

How can I check whether a option already exist in select by Prototype?

I want to dynamically add options into select and so I need to check whether the opt开发者_StackOverflow中文版ion is already exist to prevent duplication.

I already See the same question with Jquery, but i try and try without success to do it with Prototype.

Thanks for any help.

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try this

var exists = false;
$$('select#some-select-id option').each(function(el){
   if(el.value == val_to_check)
   {
      exists = true;
      throw $break;
   }
});

if(!exists) //add option

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An alternate, less verbose alternative would be to use Prototype's find() method:

var exists = !!$$('select#some-select-id option').find(function(el){ return el.value == val_to_check });