How do I check if an object has only one property or only two properties and no other property in javascript

Question

I want to check if an object has only one property or only two properties and no other property in javascript.

Suppose I have an object like this.

const obj1 = {
   a : 'something'
}

OR

const obj2 = {
  a : 'somthing',
  b : 'somthing else'
}

Now how do I check if obj1 has only a and no other property? Also, how do check if obj2 has only a and b and no other property? Thanks for your time

Look this: https://stackoverflow.com/questions/126100/how-to-efficiently-count-the-number-of-keys-properties-of-an-object-in-javascrip — burrito, Nov 29 '20 at 10:52
Key/values are referenced by `:`, not `=` - and you have missing commas... — Roko C. Buljan, Nov 29 '20 at 10:57
By the way, you need to add commas between two property declarations. — expressjs123, Nov 29 '20 at 10:59

score 4 · Accepted Answer · answered Nov 29 '20 at 10:55

4

Object.keys(obj1).length == 1 && obj1.a

and

Object.keys(obj2).length == 2 && obj2.a && obj2.b

both utilize the number of keys.

answered Nov 29 '20 at 10:55

expressjs123

1,580
1
3
17

score 1 · Answer 2 · answered Nov 29 '20 at 11:02

You may use the following countobjkey function:

<script>
function countobjkey(var1)
{let size=0;
for(let k in var1) {
  size++
}
return(size);
}



var person = {fname:"John", lname:"Doe", age:25};
var car = {engine:"X4", brand:"Toyota", cc:'1300', color:'black'};

alert(countobjkey(person));
alert(countobjkey(car));



</script>

How do I check if an object has only one property or only two properties and no other property in javascript

2 Answers2