A simple Google Apps Script for copying referenced footnotes into inline footnotes

footnote_inliner.gs

function footnoteInliner() {
  var body = DocumentApp.getActiveDocument().getBody();
    
  var searchResult = null;
  var count = 0;
  
  while (searchResult = body.findElement(DocumentApp.ElementType.FOOTNOTE, searchResult)) {
    count++;
    
    var el = searchResult.getElement();
    var elindex = 1 + el.getParent().asParagraph().getChildIndex(el);
    var contents = el.getFootnoteContents().getText();
        
    var inlineText = el.getParent().asParagraph().insertText(elindex, inlineTemplate(contents));
    inlineText.setBackgroundColor( 1, inlineTemplate(contents).length-1 , color(count) ).setForegroundColor('#000000');
  }
  if (count == 0) {
    DocumentApp.getUi().alert('No footnotes were found in this document.');
  } else {
    DocumentApp.getUi().alert('All '+count+' of your footnotes have been inlined!');
  }
}

function onOpen() {
  var ui = DocumentApp.getUi();
  ui.createMenu('Hana Tools').addItem('Inline all footnotes', 'footnoteInliner').addToUi();
}
  
function inlineTemplate(str) {
  var result = " [[" + str + "]] ";
  return result;
}

function color(n) {
  var palette = ['#FACEC8','#AAEAFC','#CAE3D2','#BFC2D5'];
  return palette[n % palette.length];
}