Take the variable proba and put it in to the Representative.get brackets

JS to ERB

<script>
function getJson(){     
			var proba='http://0.0.0.0:4568/;
			var stuff = <%= Representative.get('http://0.0.0.0:4568/') %>;
			var data = "data:image/jpeg;base64, "+stuff.imageBase64;
			setTimeout(function(){document.getElementById("X_Axis").value=stuff.acceleration.X_Axis}, 200);
			setTimeout(function(){document.getElementById("Y_Axis").value=stuff.acceleration.Y_Axis}, 400);
                        setTimeout(function(){document.getElementById("Z_Axis").value=stuff.acceleration.Z_Axis}, 600);
                        setTimeout(function(){document.getElementById("Latitude").value=stuff.latitude}, 800);
                        setTimeout(function(){document.getElementById("Longitude").value=stuff.longitude}, 1000);
                        setTimeout(function(){document.getElementById("InternalTemperature").value=stuff.internalTemperature}, 1200);
                        setTimeout(function(){document.getElementById("Light").value=stuff.light}, 1400);
                        setTimeout(function(){document.getElementById("Distance").value=stuff.distance}, 1600);
                        setTimeout(function(){document.getElementById("Range").value=stuff.range}, 1800);
                        setTimeout(function(){document.getElementById("X_Axis_").value=stuff.magneticField.X_Axis}, 2000);
                        setTimeout(function(){document.getElementById("Y_Axis_").value=stuff.magneticField.Y_Axis}, 2200);
                        setTimeout(function(){document.getElementById("Z_Axis_").value=stuff.magneticField.Z_Axis}, 2400);
			setTimeout(function(){document.getElementById("a").src=data}, 2600);
			}
</script>