Adding custom variables to an object [duplicate]

Question

Suppose I have an object obj which has some variables in it. What I want to do is to add a new variable which has a name i gave as a parameter. For example:

var obj=
{
  number:8
}

function AddField(field_name,obj)
{
  //some magical code here
}

If I call

AddField('name',obj);

i want to be able to do

obj.name='Apple'

after calling this function.

Any ideas?

You could always just call obj.name = 'Apple', if you'd tried it, you'd know it works — zzzzBov
– zzzzBov, Commented May 14, 2013 at 13:26

VisioN · Accepted Answer · 2013-05-14 13:25:32Z

5

Use square brackets notation:

obj[field_name] = value;

REF: http://www.jibbering.com/faq/faq_notes/square_brackets.html#vId

answered May 14, 2013 at 13:25

VisioN

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4 Comments

Denys Séguret Over a year ago

OP doesn't seem to want to add a value, just a field.

VisioN Over a year ago

@dystroy Then value = undefined.

Denys Séguret Over a year ago

Maybe. In fact I don't get what's the real question.

AutomaticHourglass Over a year ago

So simple, yet perfect for my need, thank you. I will accept the answer as soon as i can.

Ja͢ck · Accepted Answer · 2013-05-14 13:25:49Z

0

Use the bracket notation:

obj[field_name] = void 0;

This creates a new property with an undefined value.

answered May 14, 2013 at 13:25

community wiki

Ja͢ck

Comments

Pablo Mescher · Accepted Answer · 2013-05-14 13:29:49Z

0

If obj is already defined, you can just do obj.field_name = null or obj["field_name"] = null. I wouldn't set any value to undefined even though the language allows for that, simply for a semantic issue: undefined means "this property/variable has not been defined" and null means "this property/variable has no value".

answered May 14, 2013 at 13:29

Pablo Mescher

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