regex101: PCRE (Legacy) Match Workspace

Regular Expression

\A(?:^.*$\n){1}\K^.*$

New

{{- .Scratch.Set "pagesIndex" slice -}}
{{- range where .Site.RegularPages "Type" "in" .Site.Params.mainSections -}}
  {{- $contentRE := replaceRE "(<pre.*>(.|\n)*?</pre>)|(<code.*>(.|\n)*?</code>)|(<h[2-4].*>(.|\n)*?</h[2-4]>)|(<[^>]*>)|(\\n)|(\\t)" "" (.Content | htmlUnescape) -}}
  {{- $pageData := (dict "title" .Title "href" .RelPermalink "content" $contentRE) -}}
  {{- $.Scratch.Add "pagesIndex" $pageData -}}
{{- end -}}
{{- .Scratch.Get "pagesIndex" | jsonify -}}

Substitution

{{- .Scratch.Set "pagesIndex" slice -}}
{{- range where .Site.RegularPages "Type" "in" .Site.Params.mainSections -}}
  {{- $contentRE := replaceRE "(<pre.*>(.|\n)*?</pre>)|(<code.*>(.|\n)*?</code>)|(<h[2-4].*>(.|\n)*?</h[2-4]>)|(<[^>]*>)|(\\n)|(\\t)" "" (.Content | htmlUnescape) -}}
  {{- $pageData := (dict "title" .Title "href" .RelPermalink "content" $contentRE) -}}
  {{- $.Scratch.Add "pagesIndex" $pageData -}}
{{- end -}}
{{- .Scratch.Get "pagesIndex" | jsonify -}}