check the object length code example
Example: length of an object in javascript
//length of this object is 4
let object = {
'A':{
'10':['a','b','c']
},
'B':{
'20':['a','b','c']
},
'C':{
'30':['a','b','c']
},
'D':{
'40':['a','b','c']
},
}
//Get the keys of the object (A,B,C,D) and print how many there are
Object.keys().length
> prints: 4