adding a property to an object in javascript

Question

function addProperty(object, property) {
  // add the property to the object with a value of null
  // return the object
  // note: the property name is NOT 'property'.  The name is the value of the argument called property (a string)
}

I got a little stuck on an only home work question. I think I understand what its asking me to do. I want to pass in an object and add a new property and set its default value to null.

Here is what I have tried doing

function addProperty(object, property) {
  // add the property to the object with a value of null
  // return the object
  // note: the property name is NOT 'property'.  The name is the value 
  object.property = property;
  object[property] = null;
  return object;
    }

This does not seem to be working the way I need it to as I believe I the object should produce something like

const object = {
propertyPassedIn: null,
};

can anyone help or point me in the right direction?

function addProperty(object, property) { object[property] = null; return object; } which you said you tried (at least part of your function did). What's the problem? — Patrick Roberts
– Patrick Roberts, Commented Mar 18, 2018 at 0:31

Niccaman · Accepted Answer · 2018-03-18 00:42:41Z

3

This works for me

function addProperty(object, property) {
  // add the property to the object with a value of null
  // return the object
  // note: the property name is NOT 'property'.  The name is the value 
  // object.property = property;
  object[property] = null;
  return object;
}

var obj = {x:1,y:null};
// undefined
obj
// {x: 1, y: null}
addProperty(obj, 'z');
// {x: 1, y: null, z: null}

answered Mar 18, 2018 at 0:42

Niccaman

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Comments

Gustav P Svensson · Accepted Answer · 2025-01-15 08:54:53Z

2

The preferred way of doing this if you ask me is to use Object.assign. This will copy all the properties of the second object you pass in into the first object. You can also send in multiple objects and all will be copied into the first object.

function addProperty(object, property) {
    return Object.assign(object, { [property]: null });
}

answered Jan 15 at 8:54

Gustav P Svensson

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Comments

Code_Frank · Accepted Answer · 2018-03-18 01:52:55Z

1

Just remove

object.property = property;

from your sample. This line would create a ReferenceError if the property is not already in the object. Other than that, I can't see a reason why it wouldn't do what you say you expect.

edited Mar 18, 2018 at 1:52

answered Mar 18, 2018 at 0:48

Code_Frank

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Comments

nikhil karkra · Accepted Answer · 2018-03-18 00:58:13Z

0

function addProperty(object, property) {
  object[property] = null;
  return object;
}

    var obj = {
       key1:1,
       key2:2
    };

addProperty(obj, 'value');
this will give below result
{key1:1, key2:2, value:null}

answered Mar 18, 2018 at 0:58

nikhil karkra

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