I'm new in JavaScript programming and I have two object arrays that have the following structure:
myFirstObjArray = [{foo: 1, bar: 1}, {foo: 3, bar: 3}, {foo: 4, bar: 5}];
mySecondObjArray = [{foo: 2}, {foo: 4}, {foo: 5}];
I need to get two separate arrays containing the values of key foo
, the first containing the ones that are in the first array but not in the second, based on the value of key foo
, and the second that are in mySecondObjArray
but not in myFirstObjArray
.
Is there a way to do this without
for(i=0;i<myFirstObjArray.length;i++)
for(j=0;j<mySecondObjArray .length;j++)
{...build first array here}
for(i=0;i<mySecondObjArray .length;i++)
for(j=0;j<myFirstObjArray.length;j++)
{...build second array here}
? Perhaps my question is a duplicate one that I didn't find, so please be gentle.
Expected output:
firstArray = [{foo: 1}, {foo: 3}];
secondArray = [{foo: 2}, {foo: 5}];
You can simply filter one array's elements by setting the condition based on other array's elements like.
var myFirstObjArray = [{foo: 1, bar: 1}, {foo: 3, bar: 3}, {foo: 4, bar: 5}],
mySecondObjArray = [{foo: 2}, {foo: 4}, {foo: 5}],
firstArray = myFirstObjArray.filter(o=> !mySecondObjArray.some(i=> i.foo === o.foo));
secondArray = mySecondObjArray.filter(o=> !myFirstObjArray.some(i=> i.foo === o.foo));
console.log(firstArray.map(o=> {return {'foo' : o.foo}}))
console.log(secondArray.map(o=> {return {'foo' : o.foo}}))
Ps:
The some()
method tests whether at least one element in the array passes the test implemented by the provided function. And I've added a function which just checks if foo
property exists in the other array with the same value to be able to filter from the first array.
At the end you can use .map
to filter out the desired key value pairs
Hope that makes sense