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Javascript – Adding properties to a single object that are missing from the data object code not working

I have a data object with key-value pairs. The data object comprises 4 properties with corresponding values. However, when data is pulled from the API, it sometimes shows 2 or 3 properties like in the case below (If the data is not available for a certain property it will not show up in the object). I want to add back the missing properties to the same object as shown below.

Data Output

var obj = {
  property1: 100
  property2: 80
  property3: 50
}

I want to check within the object if property4 exists. If not, then I can add it to the same object with a boolean value i.e. false

My code that checks all properties whether they are missing, but it is not working as expected

var obj = {
  property1: 100,
  property2: 80,
  property3: 50
}
;

const property_1 = obj.hasOwnProperty('property1');
console.log(property_1);
const property_2 = obj.hasOwnProperty('property2');
console.log(property_2);
const property_3 = obj.hasOwnProperty('property3');
console.log(property_3);
const property_4 = obj.hasOwnProperty('property4');
console.log(property_4);

if (property_1 === false || property_2 === false || property_3 === false || property_4 === false)  {

obj.property1 = false
obj.property2 = false
obj.property3 = false
obj.property4 = false
 
} 

console.log(obj)

//Console Output

{
  property1: false,
  property2: false,
  property3: false,
  property4: false
}

My Expected Result is:

{
  property1: 100,
  property2: 80,
  property3: 50,
  property4: false // Does not exist, hence it is false 
}

May I know where I am going wrong?

Tags:

4

Answers


  1. 0

    Your condition

    if (property_1 === false || property_2 === false || property_3 === false || property_4 === false)  {

    is true if any of the properties were missing. Then you set all the properties to false, including the ones that already had values.

    You could just use a series of if statement for each property:

    if (!obj.hasOwnProperty('property1')) {
    obj.property1 = false;
}
if (!obj.hasOwnProperty('property2')) {
    obj.property2 = false;
}
...

    But the simple way to do this is to merge the object with an object that contains all the properties.

    var obj = {
  property1: 100,
  property2: 80,
  property3: 50
};

const defaults = {
  property1: false,
  property2: false,
  property3: false,
  property4: false
};

obj = {...defaults, ...obj};

console.log(obj);
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  2. 0

    you can’t do them all in one if statement
    you need to check them separately
    A simple way is to use tenary operator

    remove your if block and add this instead

    obj.property1=obj.hasOwnProperty('property1')?obj.property1:false;
obj.property2=obj.hasOwnProperty('property2')?obj.property2:false;
obj.property3=obj.hasOwnProperty('property3')?obj.property3:false;
obj.property4=obj.hasOwnProperty('property4')?obj.property4:false;

    e.g. https://jsbin.com/zonecejoge/edit?js,console

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  3. 0

    You could do with Nullish coalescing assignment (??=):

    var obj = {
  property1: 100,
  property2: 80,
  property3: 50
};

obj.property1 ??= false;
obj.property2 ??= false;
obj.property3 ??= false;
obj.property4 ??= false;

console.log(obj);
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  4. 0

    assuming your keys are known, you can do something like this to clean it up and get it working:

    const keys = ['property1', 'property2', 'property3', 'property4'];

var obj = {
  property1: 100,
  property2: 80,
  property3: 50
}

keys.forEach(key => {
  if (!obj.hasOwnProperty(key)) obj[key] = false;
});

console.log(obj);

    see screenshot for example output:

    enter image description here

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