Knowledge of traversal of object arrays

for(name in object){}; traverse the object{};

for(var i=0;i<name.length;i++){};traverse

the array; print as a string: JSON.stringify(sht); console.log()

judges whether the object contains sths.hasOwnProrert(sth);//If it contains elements, the return value is true, if it does not contain elements, the return value is false;