Dataviewjs List of Frontmatter Values

What I’m trying to do

What I’m trying to do is create a dataviewjs query that checks if there is any values in my source property and if so list them like this “<- [value1], [value2], [value3]”

I’m essentially trying to do this

*<-`= this.source`* 

but in a way that doesn’t show the arrow and empty list if there arent any values in the source property.

Things I have tried

let source = dv.current().file.frontmatter.source;

if (source > 0) {
  dv.el('span', `*<- ${dv.array(source)}*`);
}