There are two different ways of getting the desired result
The first method is iterating through each collection using for loop and displaying the result
cols = db.getCollectionNames();
for (index = 0; index < cols.length; index++) {
var coll = db.getCollection(cols[index]);
var stats = coll.stats();
print(stats.ns, stats.count, stats.size, stats.totalIndexSize); }
OR
The secondΒ method is iterating through eachΒ collection using cursorΒ which in turns call function
var stats;db.getCollectionNames().forEach(function(x) { stats=db.getCollection(x).stats(); print(stats.ns, stats.count, stats.size, stats.totalIndexSize); });
Prashanth Jayaram 
