function ajax(url,postData) {
	let request = new XMLHttpRequest();
	let method = postData ? 'POST' : 'GET';
	request.open( method, url );
	let isMultipart = postData instanceof File;
	if( postData && !isMultipart )
		request.setRequestHeader( 'Content-Type', 'application/x-www-form-urlencoded' );
	request.onload = function() {
		if( request.status !== 200 ) {
			window.console && console.log( 'ajax failed: ' + request.status );
			if( request.responseText )
				document.write('<pre>'+request.responseText+'</pre>');
			return;
		}
		eval( request.responseText );
	};
	if(isMultipart) {
		let formData = new FormData();
		formData.append( 'file', postData );
		request.send(formData);
	} else {
		request.send(postData);
	}
}

window.onerror = function(msg, url, line, col, error) {
	if (!url)
		return;
	let err = msg;
	err += '\nurl = ' + url;
	if (url != window.location)
		err += '\npage = ' + window.location;
	err += '\nline = '+line;
	if (col)
		err += '\ncolumn = ' + col;
	if (error && error.stack)
		err += '\nstack = ' + error.stack;
	ajax( '/error_log.js', 'err='+encodeURIComponent(err) );
};