Here’s another little Docs annoyance that can easily be cleaned up with a little automation. If you are using headings in your document, and insert blank lines beside a heading, you end up with uneven blank lines since they will take the format of the heading level rather than just a normally spaced line. Here’s a snippet to clean that up.

Cleaning up blank lines in a document

The hierarchy array lists out all the heading levels to consider for conversion. I guess there may be some reason that you want to exclude some.

// this is the list of heading types to convert..(them all in this case)
  var heirarchy = [ 
    DocumentApp.ParagraphHeading.HEADING1,
    DocumentApp.ParagraphHeading.HEADING2,
    DocumentApp.ParagraphHeading.HEADING3,
    DocumentApp.ParagraphHeading.HEADING4,
    DocumentApp.ParagraphHeading.HEADING5,
    DocumentApp.ParagraphHeading.HEADING6,
    DocumentApp.ParagraphHeading.SUBTITLE,
    DocumentApp.ParagraphHeading.TITLE
  ];

The demote variable says what heading level matching blank paragraphs should be set to.

// what to set blank lines to,normally it would be normal
  var demote = DocumentApp.ParagraphHeading.NORMAL;

This function provides a dry run capability that reports which headings it plans to demote, then set this false when ready to commit.
var DRY_RUN = false;

Here’s the kind of update you get.

adjusting paragraph 0 from Title to Normal
adjusting paragraph 2 from Title to Normal
adjusting paragraph 3 from Title to Normal
adjusting paragraph 4 from Title to Normal
adjusting paragraph 7 from Subtitle to Normal
adjusting paragraph 1059 from Heading 3 to Normal
adjusting paragraph 1137 from Title to Normal
adjusting paragraph 1138 from Title to Normal
adjusting paragraph 1149 from Heading 3 to Normal
adjusting paragraph 1248 from Heading 2 to Normal
adjusting paragraph 1301 from Heading 3 to Normal

And that’s all there is to it. Here’s the code

// blank lines in documetns are sometimes set to header levels rather thannoemal text.
// this converts them to normal text
function demoteHeaderLevels () {
  
  var doc = DocumentApp.getActiveDocument();
  
  // set this to false when it looks like it does what's needed
  var DRY_RUN = true;
  
  // this is the list of heading types to convert..(them all in this case)
  var heirarchy = [ 
    DocumentApp.ParagraphHeading.HEADING1,
    DocumentApp.ParagraphHeading.HEADING2,
    DocumentApp.ParagraphHeading.HEADING3,
    DocumentApp.ParagraphHeading.HEADING4,
    DocumentApp.ParagraphHeading.HEADING5,
    DocumentApp.ParagraphHeading.HEADING6,
    DocumentApp.ParagraphHeading.SUBTITLE,
    DocumentApp.ParagraphHeading.TITLE
  ];

  // what to set blank lines to,normally it would be normal
  var demote = DocumentApp.ParagraphHeading.NORMAL;
  
  doc.getBody().getParagraphs().forEach (function (d,i) {
    
    var heading = d.getHeading();
    var idx = heirarchy.indexOf(heading);
    
    // check it's an interesting one
    if (idx !== -1) {
      
      // if only blank then demote to normal text
      if (!d.getText().replace(/\s/gmi,"")) {
        if (!DRY_RUN) {
          d.setHeading (demote);
        }
        Logger.log( (DRY_RUN ? ' would have adjusted' : ' adjusting') + 
          ' paragraph ' + i + ' from ' + heading + ' to ' + demote);
      }
    }
  });
  }

For more like this see Google Apps Scripts Snippets
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