Why is the code not sent to the iskraJS microcontroller using the UART library?

I am using the UART.js library and iskraJS microcontroller .
Espruino Web IDE is used to program this microcontroller

document.body.onclick =  function()
	{
		UART.connect(
			function(connection) 
			{
			    if (!connection) throw "Error!";
			    connection.write("var on = false;setInterval(function() {on = !on;LED1.write(on);}, 5000);", function(){ });
		  	}
		)
	}