Google Earth Engine: Stack an ImageCollection

Question

Does anyone know how can I stack all this collection?

I made my own collection from January Landsat images (L7 and L5) and I would like to stack all the images to check which are the areas with more data (without clouds).

var col = imageCollection
  .sort('system:time_start')
  .filterBounds(region)
  .map(function(image) {
    var date = ee.Date(image.get('system:time_start'));
    var savi = image.expression(
      '(1 + L) * float(nir - red)/ (nir + red + L)',
      {
        'nir': image.select('B4'),
        'red': image.select('B3'),
        'L': 0.5
      });
      var mask = image.select(['cfmask']).neq((1,2,3,4));
    return ee.Image(1).addBands(savi).updateMask(mask);
  });

Answer 1

I gather that you want to combine multiple image collections into a single one. To do that, you first have to make sure both collections have exactly the same bands. Then you simply call merge()

var l5 = ee.ImageCollection('LANDSAT/LT05/C01/T1_SR')
  .select( // Select and rename bands to a normalized set of bands/band names
    ['B1', 'B2', 'B3', 'B4', 'B5', 'B6', 'B7', 'pixel_qa'],
    ['blue', 'green', 'red', 'nir', 'swir1', 'thermal', 'swir2', 'pixel_qa']
  )
var l7 = ee.ImageCollection('LANDSAT/LE07/C01/T1_SR')
  .select( // Select and rename bands to a normalized set of bands/band names
    ['B1', 'B2', 'B3', 'B4', 'B5', 'B6', 'B7', 'pixel_qa'],
    ['blue', 'green', 'red', 'nir', 'swir1', 'thermal', 'swir2', 'pixel_qa']
  )
var imageCollection = l5.merge(l7)