SplitPages.js

ProcessDocument = app.trustedFunction(function () {
    app.beginPriv();
	var newDoc = app.newDoc();

	var p = app.response("Start with page(default 0 - process all pages)?", "Query", "0");
	var startFrom = parseInt(p) || 0;
	var i = 0;
	while (i < this.numPages) {
		newDoc.insertPages({
			nPage: newDoc.numPages - 1,
			cPath: this.path,
			nStart: i
		});
		if (i >= startFrom) {
			newDoc.insertPages({
				nPage: newDoc.numPages - 1,
				cPath: this.path,
				nStart: i
			});
		}

		i++;
	}

	if (newDoc.numPages > 1) {
		newDoc.deletePages(0);
	}

	for (var i = 0; i < newDoc.numPages; i++) {
		if (i < startFrom) continue;

		var cropRect = newDoc.getPageBox("Crop", i);
		var halfWidth = (cropRect[2] - cropRect[0]) / 2;

		var cropLeft = new Array();
		cropLeft[0] = cropRect[0];
		cropLeft[1] = cropRect[1];
		cropLeft[2] = cropRect[0] + halfWidth;
		cropLeft[3] = cropRect[3];

		var cropRight = new Array();
		cropRight[0] = cropRect[2] - halfWidth;
		cropRight[1] = cropRect[1];
		cropRight[2] = cropRect[2];
		cropRight[3] = cropRect[3];

		if (i % 2 == 0) {
			newDoc.setPageBoxes({
				cBox: "Crop",
				nStart: i,
				rBox: cropLeft
			});
		} else {
			newDoc.setPageBoxes({
				cBox: "Crop",
				nStart: i,
				rBox: cropRight
			});
		}

	}
	app.endPriv();
});

app.addMenuItem({
	cName: "splitPagesJS",
	cUser: "Split Pages",
	cParent: "Document",
	cExec: "ProcessDocument()",
	cEnable: "event.rc = (event.target != null);",
	nPos: 0
});
app.addToolButton({
	cName: "splitPagesJSTB",
	cExec: "ProcessDocument()",
	cTooltext: "Split Pages",
	cLabel: "Split Pages",
	cEnable: true,
	nPos: 0
});

hi, altmind
your script is a good work, but i have only one problem. it is about right-to-left pdf files, i can split them with no errors except for i get the reverse order of odd and even pages, so i have to extract all pages rename and combine again. i wondered if this can be fixed in the script.
if you have time to fix this I'll be appreciating.
thanks in advance.

An odd problem I found. When I choose an odd-numbered page for the page to start on, the pages go out of order (15, 14, 17, 16, etc). When I choose an even-numbered page for the start page, the pages are in order.