javascript - Loop through all keys of multiple objects once? -

i have array of object-names

['obj','obj2','objn'] 

these objects nodes in object

{   obj: {     key: value,     key2: value,   }   obj2:{     key3: value   } ... } 

i know 1 object can do:

for (var key in obj) {   if (obj.hasownproperty(key)) {     console.log(key)   } } 

but possible loop through keys of multiple objects without doing duplicates?

assuming parent container object form:

var parentobj =  {     obj: {         key: value,         key2: value,     }     obj2: {         key3: value     }     ... } 

also if want include each sub-key once, have

var objnamearray = ['obj','obj2','objn']; var allvalues = []; var usedkeys = {};  for(var = 0; < objnamearray.length; ++i){     // if parent object not have matching sub-object, skip     // next iteration of loop     if(!parentobj[objnamearray[i]]) {         continue;     }     var currentobj = parentobj[objnamearray[i]];     var subkeys = object.keys(currentobj);     for(var j = 0; j < subkeys.length; ++j) {         if(usedkeys[subkeys[j]]) {             continue;         }         usedkeys[subkeys[j]] = true;         allvalues.push(currentobj[subkeys[j]]);     } } 

all values keys in each sub-object in array allvalues, , keys each sub-object available calling object.keys(usedkeys);. note if sub-objects can have sub-objects, strategy needs adapted support recursion.