QA60 band to mask clouds

step 1: import the image

// import image
var image = ee.Image("COPERNICUS/S2/20170101T050212_20170101T050737_T44NLN");

step 2: select the qa band

// get QA band
var QA ="??");

step 3: Get the cloud and cirrus mask

// Bits 10 and 11 are clouds and cirrus, respectively.
var clouds = QA.bitwiseAnd(Math.pow(2, 10)).eq(0);
var cirrus = QA.bitwiseAnd(Math.pow(2, 11)).eq(0);

step 4: mask the clouds and cirrus

// mask clouds and cirrus
var imageNoClouds = image.updateMask(clouds).updateMask(cirrus);

step 5: display the bands

// add image to layer
Map.addLayer(clouds,{min:0,max:??},"cloud mask");
Map.addLayer(cirrus,{min:0,max:??},"cirrus mask");
Map.addLayer(imageNoClouds,{min:0,max:3000,bands:"??"},"masked image");