Set Custom field Value using Javascript

unknown

Hello, 

Im having abit of trouble using javascript to set a customfield value. 

I had did some research and testing but is still unable to get it to work. 

Here is the following snippet im trying: 

 

<script type="text/javascript">

 issue.getelementbyid("customfield_10301").val("test")

</script>

Any advice would be great, thanks, Pon

Evgeny Kravchenko

<script type="text/javascript">

AJS.$("#customfield_13600").val("default value");

</script>