Change object property based on variable

Question

I have an object like this

{"first":["first 1"],"second":["second 1","second 2"],"third":["third 1", "third 2"]}

I want to be able to change a property name based on a variable value. If the variable is "second" it should change the property second to whatever i want. I have tried some methods...

This

object[theVariable] = "new second";

Will change the value of the property to this

{"first":["first 1"],"second":"new second","third":["third 1", "third 2"]}

And this

object.theVariable = "new second";

Will create a new property like this

{"first":["first 1"],"second":["second 1","second 2"],"third":["third 1", "third 2"],"theVariable":"new second"}

None of these methods change the property "second" to "new second" when "second" is stored in the variable "theVariable"

Desired result:

{"first":["first 1"],"new second":["second 1","second 2"],"third":["third 1", "third 2"]}

How can this be done?

Possible duplicate of [change property name](http://stackoverflow.com/questions/8483425/change-property-name) — melpomene, Jan 16 '17 at 14:45

score 1 · Accepted Answer · answered Jan 16 '17 at 14:47

1

If I'm understanding correctly, you want to change the name of a property in your object. This should work.

object.new_second = object.second;
delete object.second

answered Jan 16 '17 at 14:47

Austin

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Weedoze · Answer 2 · 2017-01-16T14:55:03.910

1

var obj = {"first":["first 1"],"second":["second 1","second 2"],"third":["third 1", "third 2"]};

var theVariable = "new second";

obj[theVariable] = obj.second;
delete obj.second;

console.log(obj);

edited Jan 16 '17 at 14:55

answered Jan 16 '17 at 14:50

Weedoze

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@Koiski Updated answer ! – Weedoze Jan 16 '17 at 14:55

Igor · Answer 3 · 2017-01-16T14:50:29.390

-2

Use property access through bracket notation:

    var obj = {
      "first":["first 1"],
      "second":["second 1","second 2"],
      "third":["third 1", "third 2"]
    };
    console.log(obj);
    var propNameVariable = "second";
    obj[propNameVariable] = "new second";
    console.log(obj);

edited Jan 16 '17 at 14:50

answered Jan 16 '17 at 14:49

Igor

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this does not change "second" to "new second". This just replaces the value – Koiski Jan 16 '17 at 14:55
@Koiski - are you saying that you want the code to understand that the name of a new property is `"new " + `, delete the old property and set the new property? – Igor Jan 16 '17 at 15:03

Change object property based on variable

3 Answers3