Extracting an object from another object

Question

I would like to extract an object from another object, and keep the extracted object as separate independent variable and have it no longer part of the first object. The following seems to do so but seems a little convoluted. What is the correct way to do so?

function printIt(name,o) {
  //Do this way so I can see what object was at given time.
  console.log(name,JSON.stringify(o))
}
var o = {
  a: 123,
  b: {
    a: 111,
    b: 222,
    c: [3, 2, 1]
  },
  c: {
    a: 321,
    b: 123,
    c: [1, 2, 3]
  }
};
printIt("o0", o);

var o_b = o.b;

printIt("o_b1", o_b);
printIt("o1", o);

o_b.a = 444;
o.b.c=666;

printIt("o_b2", o_b);
printIt("o2", o);

delete o.b;

printIt("o_b3", o_b);
printIt("o3", o);

https://jsfiddle.net/zn0asewb/1/

o0 {"a":123,"b":{"a":111,"b":222,"c":[3,2,1]},"c":{"a":321,"b":123,"c":[1,2,3]}}
o_b1 {"a":111,"b":222,"c":[3,2,1]}
o1 {"a":123,"b":{"a":111,"b":222,"c":[3,2,1]},"c":{"a":321,"b":123,"c":[1,2,3]}}
o_b2 {"a":444,"b":222,"c":666}
o2 {"a":123,"b":{"a":444,"b":222,"c":666},"c":{"a":321,"b":123,"c":[1,2,3]}}
o_b3 {"a":444,"b":222,"c":666}
o3 {"a":123,"c":{"a":321,"b":123,"c":[1,2,3]}}

LoganRx · Accepted Answer · 2017-08-13 20:04:38Z

1

Not exactly sure why you need to be doing this with the object keys but I would look at using Object.assign. Something like:

var o = {
  a: 123,
  b: {
    a: 111,
    b: 222,
    c: [3, 2, 1]
  },
  c: {
    a: 321,
    b: 123,
    c: [1, 2, 3]
  }
};

var b = Object.assign({}, o.b)
delete o.b;

console.log(o) // { a: 123, c: { a: 321, b: 123, c: [ 1, 2, 3 ] } }
console.log(b) // { a: 111, b: 222, c: [ 3, 2, 1 ] }

answered Aug 13, 2017 at 20:04

LoganRx

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