Looking for variables which aren't assigned

What could happen if my template looks for variables which weren't assigned?

For example:

var id = '{$tpl_id}';

This snippet is from my javascript code. I outputted the value and it 开发者_运维知识库is simply empty. I know I could use isset(). But I couldn't find anything about how Smarty handles non-existing variables. So, what happens if a template can't find a variable, because it wasn't assigned?

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If a variable isn't defined, it's treated as if it were an empty variable. No (non-logic) error will occur.

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Hy You have to use {literal} {/literal} Example:

{literal}
<script>
var id = '{/literal}{$tpl_id}{literal}';
// keep coding
</script>
{/literal}