script.js

//VERSION=3

//Basic initialization setup function
function setup() {
  return {
	//List of all bands, that will be used in the script, either for visualization or for choosing best pixel
    input: [{
      bands: [
         "B04",
         "B08"
      ]
    }],
	//This can always be the same if one is doing RGB images
    output: { bands: 3 },
    mosaicking: "ORBIT"
  }
}

/*
In this function we limit the scenes, which are used for processing. 
These are based also on input variables. 
E.g. if one sets date "2017-03-01" ("TO date") and cloud coverage filter 30%, 
all scenes older than 2017-03-01 with cloud coverage 30% will be checked against
further conditions in this function.
The more scenes there are, longer it will take to process the data.
After 60 seconds of processing, there will be a timeout.
*/

function preProcessScenes (collections) {
    collections.scenes.orbits = collections.scenes.orbits.filter(function (orbit) {
        var orbitDateFrom = new Date(orbit.dateFrom)
        return orbitDateFrom.getTime() >= (collections.to.getTime()-3*31*24*3600*1000);
    })
    return collections
}

function calcNDVI(sample) {
  var denom = sample.B04+sample.B08;
  return ((denom!=0) ? (sample.B08-sample.B04) / denom : 0.0);
}
function evaluatePixel(samples) {  
  var max = 0;
  for (var i=0;i<samples.length;i++) {
      var ndvi = calcNDVI(samples[i]);
    max = ndvi > max ? ndvi:max;
  }
if (max<-1.1) return [0,0,0];
else if (max<-0.2) return [0.75,0.75,0.75];
else if (max<-0.1) return [0.86,0.86,0.86];
else if (max<0) return [1,1,0.88];
else if (max<0.025) return [1,0.98,0.8];
else if (max<0.05) return [0.93,0.91,0.71];
else if (max<0.075) return [0.87,0.85,0.61];
else if (max<0.1) return [0.8,0.78,0.51];
else if (max<0.125) return [0.74,0.72,0.42];
else if (max<0.15) return [0.69,0.76,0.38];
else if (max<0.175) return [0.64,0.8,0.35];
else if (max<0.2) return [0.57,0.75,0.32];
else if (max<0.25) return [0.5,0.7,0.28];
else if (max<0.3) return [0.44,0.64,0.25];
else if (max<0.35) return [0.38,0.59,0.21];
else if (max<0.4) return [0.31,0.54,0.18];
else if (max<0.45) return [0.25,0.49,0.14];
else if (max<0.5) return [0.19,0.43,0.11];
else if (max<0.55) return [0.13,0.38,0.07];
else if (max<0.6) return [0.06,0.33,0.04];
else return [0,0.27,0];

}