Conditionally setting a variable voids the value when the condition path is not taken

[chriskirknielsen]

Hello, and sorry for the potentially confusing title.

I am using Vento via eleventy-plugin-vento for Eleventy, but have managed to replicate the issue in the Vento playground. If a value already exists (in my case, from a template file or a global data value), if I try to overwrite it conditionally, without an else clause, the value is voided/null/empty if the condition is falsy.

{{> url = 'abc' }}
{{ if path }}{{ set url = path }}{{ /if }}
My url value is: {{ url }}

With the example above, if my global data has a url variable (simulated with the first line of JS), but no path variable, the if block should be skipped. However, this produces an empty value. If I remove the if line, the url value is printed as expected.

I don't know exactly how data is fed in the plugin but given I get the same behaviour with just these three lines with Vento in the playground, I would imagine the same underlying issue occurs.

Similarly, if I run the following code with the same conditions (url truthy, path falsy), the variable returns null:

{{ set url = url || path || null }}

I am working around it for now by declaring new variables, but would love for the standard JavaScript reassignment feature to work the same in Vento.

Please let me know if you need more info or examples, I'd be happy to provide them.

Thanks!

[oscarotero]

It's caused by declaring the variable manually with {{> url = 'abc' }} and then override it with set. Declaring it with {{ set url = 'abc' }} fixes it.

The reason is that set tag is compiled to this:

// {{ set url = path }}

var url = path;
it["url"] = url;

As you can see, the variable is defined twice, once as var url and then stored into it["url"].
This allows to consume the variable later as url or it.url (var makes the variable available globally, even outside the if).
But this was implemented before Vento transformed the code automaticaly to convert all variables to it[varname]. So this is no longer necessary. And the existence of two variables is what cause the bug in the code conversion.

After doing some tests, seems that the code can be compiled as this without errors:

// {{ set url = path }}

it["url"] = path;

So I just fixed that and am going to release a new patch.

[chriskirknielsen]

Thank you for explaining the issue, I truly appreciate understanding why this was happening! And thank you so much for the patch, I'm eager to give it a try!

EDIT: Confirming this fixes my particular use case. Thank you! 🎉