Indesign script for converting page numbers to percentages.

Page Numbers To Percentages.jsx

// Version.1.0.
// Page Numbers To Percentages.jsx
// https://gist.github.com/joonaspaakko/6628e2b6252d622b1b7f7eba601f6c91

// You may want to save before running the script. Every single
// time you run the script, all text frames that are inside a
// master page or nested master pages will be torn out (overridden).

// The script assumes the starting point is this:
// 1. You have a designated layer for the page numbers (Layer name defined below↓).
// 2. The layer should only contain one empty textframe per page. The text frame could contain text too, but it will be overweritten so it doesn't really matter.
//    - The text frame can be inside a master page or a regular page.


var layerName = "Page Numbers";
var basedOn = 1; // 0 = Puts back the current page number, 1 = The numbered pages, 2 = All pages
var percentage_prefix = '';
var percentage_suffix = '%';

if ( app.documents.length > 0 ) {
	
	var doc = app.activeDocument;
	var targetLayer = null;
	var layer = doc.layers.itemByName( layerName );
	var numberItems = prepareNumberOverride( doc, layer );
	replacePageNumbers( layer, numberItems );
	
}


function prepareNumberOverride( doc, layer ) {
	
	var collect_items = [];

	for ( var pageIndex=0; pageIndex < doc.pages.length; pageIndex++ ) {
		
		var page = doc.pages[pageIndex];
		var nPageItems = page.textFrames;
		var mPageItems = page.masterPageItems;
		
		
		var pageItemAdded = false;
		for ( var nPageItemIndex=0; nPageItemIndex < nPageItems.length; nPageItemIndex++ ) {
			var textFrame = nPageItems[ nPageItemIndex ];
			if ( textFrame.itemLayer == layer ) {
				collect_items.push( textFrame );
				pageItemAdded = true;
			}
		}
		
		if ( !pageItemAdded ) {
			for ( var mPageItemIndex=0; mPageItemIndex < mPageItems.length; mPageItemIndex++ ) {
				
				var item = mPageItems[ mPageItemIndex ];
				if ( item.itemLayer === layer ) {
					
					var text = item.contents;
					
					item.allowOverrides = true;
					if ( item.allowOverrides == true ) {
						var newItem = item.override( page );
						collect_items.push( newItem );
					}
					
				}
				
			}
		}
	
	}
	
	return collect_items;
	
}

function replacePageNumbers( layer, numberItems ) {
	
	var numberItemsLength = numberItems.length;
	
	for ( var i=0; i < numberItems.length; i++ ) {
		
		var numberItem = numberItems[i];
		var currentPageNumber = numberItem.parentPage.name;
		
		// Based on all number pages...
		if ( basedOn == 1 ) {
			var percentage = Math.floor( ((i+1) / numberItemsLength) * 100 );
		}
		// Based on all pages...
		else if ( basedOn == 2 ) {
			var percentage = Math.floor( (currentPageNumber / app.activeDocument.pages.length) * 100 );
		}
		
		numberItem.contents = basedOn == 0 ? currentPageNumber : percentage_prefix + percentage + percentage_suffix;
		
	}
	
}