Best way to Check a JavaScript Object has all the keys of another JavaScript Object - Stack Overflow

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I have two JS objects, I want to check if the first Object has all the second Object's keys and do something, otherwise, throw an exception. What's the best way to do it?

function(obj1, obj2){
    if(obj1.HasAllKeys(obj2)) {
         //do something
    }
    else{
         throw new Error(...);
    } 
};

For example in below example since FirstObject has all the SecondObject's key it should run the code :

FirstObject
{
    a : '....',
    b : '...',
    c : '...',
    d : '...'
}
SecondObject
{    
    b : '...',    
    d : '...'
}

But in below example I want to throw an exception since XXX doesnt exist in FirstObject:

FirstObject
{
    a : '....',
    b : '...',
    c : '...',
    d : '...'
}
SecondObject
{    
    b : '...',    
    XXX : '...'
}

I have two JS objects, I want to check if the first Object has all the second Object's keys and do something, otherwise, throw an exception. What's the best way to do it?

function(obj1, obj2){
    if(obj1.HasAllKeys(obj2)) {
         //do something
    }
    else{
         throw new Error(...);
    } 
};

For example in below example since FirstObject has all the SecondObject's key it should run the code :

FirstObject
{
    a : '....',
    b : '...',
    c : '...',
    d : '...'
}
SecondObject
{    
    b : '...',    
    d : '...'
}

But in below example I want to throw an exception since XXX doesnt exist in FirstObject:

FirstObject
{
    a : '....',
    b : '...',
    c : '...',
    d : '...'
}
SecondObject
{    
    b : '...',    
    XXX : '...'
}

• javascript
• object

Share Improve this question Follow edited Nov 6, 2018 at 15:44 Am1rr3zA asked Nov 19, 2015 at 21:28 Am1rr3zAAm1rr3zA 7,4411818 gold badges8787 silver badges134134 bronze badges

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4 Answers 4

Sorted by: Reset to default 5

You can use:

var hasAll = Object.keys(obj1).every(function(key) {
  return Object.prototype.hasOwnProperty.call(obj2, key);
});
console.log(hasAll); // true if obj2 has all - but maybe more - keys that obj1 have.

As a "one-liner":

var hasAll = Object.keys(obj1).every(Object.prototype.hasOwnProperty.bind(obj2));

You can write a function to iterate and check:

function hasAllKeys(requiredObj, secondObj) {
    for (var key in requiredObj) {
        if (!secondObj.hasOwnProperty(key)) {
            return false;
        }
    }

    return true;
}

hasAllKeys(SecondObject, FirstObject);

You can use jQuery's $.map method as follows:
$.map(a,function(value, key) {return b[key];}).length != b.length

Another way to do this, that seems to work fine as well.

   const o1 = {
              a : '....',
              b : '...',
              c : '...',
              d : '...'
            },

         o2 = {
             b : '...',
             d : '...',
          };

///////////////////////
///// I. IN ONE LINE
///////////////////////
/**/
/**/  if(Object.keys(o2).every(key =>
/**/       key in o1
/**/       // Object.keys(o1).includes(key)
/**/       // Object.keys(o1).filter(x => x==key).length
/**/  ))
/**/  console.log(true);
/**/  else throw new Error("...");
/**/
///////////////////////


///////////////////////
///// II. IN A FUNCTION
///////////////////////
/**/
/**/    var hasAll = (o1 , o2) => {
/**/      let r = Object.keys(o2).every(key =>
/**/        // Object.keys(o1).includes(key)
/**/        // key in o1
/**/        // Object.keys(o1).filter(x => x==key).length
/**/
/**/         Object.keys(o1)
/**/         .reduce((acc,act,arr) =>
/**/            acc && (key in o1) // , true
/**/         )
/**/
/**/      );
/**/      return r;
/**/    }
/**/
/**/ let cond = hasAll(o1 , o2);
/**/
/**/ console.log(cond);
/**/
/**/ if (cond) console.log(true)
//   /**/ else throw new Error("At least, one key doesn'e exist");
/**/
/**/ ////////
/**/
/**/ cond = hasAll(o2 , o1);
/**/
/**/ console.log(cond);
/**/
/**/ if (cond) console.log(true)
/**/ else throw new Error("At least, one key doesn'e exist");
/**/
///////////////////////

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