Calculate zonal statistics by longitude bin and chart the result in Earth Engine

earth_engine_zonal_stats_by_lon.js

// Load VIIRS NDVI  - to be summarized by longitude bins.
var viirsNdvi = ee.ImageCollection("NOAA/VIIRS/001/VNP13A1")
  .select('NDVI').first();

// Load lat/lon image - select the longitude band.
var latLon = ee.Image.pixelLonLat().select('longitude');

// Make a list of longitude bin start values.
var step = 5; // longitude step
var lonStarts = ee.List.sequence(-90, 90-step, step);

// Map of the longitude list - get the mean NDVI value for pixels in given
// longitude bin. Returns a list of features.
var lonStatList = lonStarts.map(function(lon) {
  var startLon = ee.Number(lon);
  var endLon = startLon.add(step);
  var targetPixels = latLon.gte(startLon).and(latLon.lt(endLon));
  var stat = viirsNdvi.updateMask(targetPixels).reduceRegion({
    reducer: ee.Reducer.mean(),
    geometry: ee.Geometry.Rectangle(-179.99, -89.99, 179.99, 89.99),
    scale: 10000,
    bestEffort: true});
  return ee.Feature(viirsNdvi.geometry(), stat).set('lon', lon);
});

// Convert feature list to feature collection.
var lonStatsCol = ee.FeatureCollection(ee.List(lonStatList));

// Chart the results.
var chart =
  ui.Chart.feature.byFeature(lonStatsCol, 'lon', 'NDVI')
    .setOptions({
      title: 'Average NDVI by Longitude',
      hAxis: {title: 'Longitude'},
      vAxis: {title: 'NDVI (x1e4)'}
    });
print(chart);