If you don’t like writing cumbersome HTML-esque markup, you can use any templating language to make the task easier.
// Jade/Pug example
a-scene(
fog='type: linear; far: 20; color: #1a1a1a'
)
a-entity(
position='2 2.5 0'
rotation='0 12 0'
)
each foo,index in locals.bar
a-entity(
position=(index * 1.4) + ' 0 ' + (index * -2)
rotation='0 ' + (index * -15) + ' 0'
)