WordPress: Add link button to export posts into a Excel file

gistfile1.js

jQuery(document).ready(function($) {
	if(typeof(pagenow) !== 'undefined' && pagenow == 'edit-post') {
                $('h2 .add-new-h2').after('<a id="data_output" class="add-new-h2" href="?ay_output=excel" target="_blank">輸出 Excel 會員列表</a>');
        }
});

gistfile2.php

<?php

add_action( 'admin_init', 'ay_output' );

function ay_output() {

	if ( isset( $_GET['ay_output'] ) && 'excel' == $_GET['ay_output'] && current_user_can( 'publish_posts' ) ) {
		// Error reporting
		error_reporting( E_ALL );

		//date_default_timezone_set( 'Asia/Taipei' );

		// PHPExcel
		requay_once 'lib/PHPExcel.php';

		// Create new PHPExcel object
		$objPHPExcel = new PHPExcel();
		$objPHPExcel->createSheet();

		// TODO: Loop to generate Rows, Columns, Cells

		// set sheet0 as default when opening the excel
		$objPHPExcel->setActiveSheetIndex( 0 );

		// Redirect output to a client’s web browser (Excel5)
		header( 'Content-Type: application/vnd.ms-excel' );
		header( 'Content-Disposition: attachment;filename="data_' . date( 'Ymd' ) . '.xls"' );
		header( 'Cache-Control: max-age=0' );

		$objWriter = PHPExcel_IOFactory::createWriter( $objPHPExcel, 'Excel5' );
		$objWriter->save( 'php://output' );
		exit;
	}
}