Keeping only certain properties in a JavaScript object

Question

I have an object. I would like to modify the object (not clone it) by removing all properties except for certain specific properties. For instance, if I started with this o

Answer 1

I Made this short solution for case where I have an array with objects.

so consider the array below?

arr=[{"a1":"A1","b1":"B1"},{"a1":"Z1","b1":"X1"}];
console.log(arr);

I want to keep only "b1" properties of all objects.

You can use map() and delete for that as follows:

arr=[{"a1":"A1","b1":"B1"},{"a1":"Z1","b1":"X1"}];
arr=arr.map(function(d){
        delete d["a1"];
        return d;

    });
console.log(arr);

result is an array with objects but only "b1" properties.