So, I don’t know if you still need the explanation:
{{ range $index, $element := .Pages }} <-- this bit goes through all the child pages in the list
{{ $element }} <-- one child page, ie .Pages[$index]
<br>
{{ $cover := $element.Resources.GetMatch "cover.jpg" }} <-- grabs the resource matching "cover.jpg"
{{ with $cover }} <-- checks if $cover exists
{{ .RelPermalink }} <-- only gets run if 'with' statement is true
{{ end }}
{{ end }}
So you would modify that to do:
{{ $coverUrl := "" }}
{{ with $cover }}
{{ $coverResized := $cover.Resize "926x q90" }}
{{ $coverUrl = $coverResized.RelPermalink }}
{{ end }}
... do stuff with {{ $coverUrl }} here ...
A minor point:
You don’t really need to .Scratch
here (unless you really want to…)
Your code above could be rewritten as:
{{ $cover := $element.Resources.GetMatch "cover.jpg" }}
{{ $coverUrl := "" }}
{{ if $cover }}
{{ $coverResized := $cover.Resize "926x q90" }}
{{ $coverUrl = $coverResized.RelPermalink }}
{{ end }}
<div class="blog-cover lazy" data-src="{{ $coverUrl }}">
<a href="{{ .Permalink }}"></a>
</div>
{{ $coverImg := .Page.Resources.GetMatch "cover.jpg" }}
{{ $cover := "" }}
{{ if $coverImg }}
{{ $resizedCover := $coverImg.Resize "2000x q90" }}
{{ $cover = $resizedCover.RelPermalink }}
{{ end }}
$cover: {{ $cover }}