Renaming or setting object names dynamically in JavaScript

Question

I'm fairly new to JavaScript I setup below to use keys and values for different items I need to work. All the values will be the same using a variable to distinguish each item (which will just be it, but I would like to identify each item (itemObject) which I'm also using for the variable name.

Abbreviated example::

function objFunction (itemName) {
    itemObject = {
        object1Data: [{
            data1: {
                prop1: 'value',
                prop2: 'value'
            },
            data2: {
                prop1: itemName + 'some string'
                prop2: itemNamevariable
            }
        }],
        object2: {
            data: {
                prop1: itemName,
                prop2:  itemName + 'some string'
            }
        }
     }
}

Or am I better off using a constructor or another method?

function ObjFunction (itemName) {
    this.itemObject = {
        bject1Data: [{
            data1: {
                prop1: 'value',
                prop2: 'value'
            },
            data2: {
                prop1: itemName + 'some string',
                prop2: itemName
            }
        }],
        object2: {
            data: {
                prop1:  itemName,
                prop2:  itemName + 'some string'
            }
        }
     }
}

var item1 = new ObjFunction('item1Name');

It's unclear what you're asking. Are you trying to somehow link those properties with the variable such that when the variable changes, those properties change automatically? Or....? — T.J. Crowder
– T.J. Crowder, Commented Dec 4, 2015 at 18:03
Your first example works (provided itemNamevariable is meant to be itemName), but A) Falls prey to The Horror of Implicit Globals, and 2) Doesn't return itemObject. (Your second example also works, but you don't need a constructor just to create an object.) — T.J. Crowder
– T.J. Crowder, Commented Dec 4, 2015 at 18:04
Yes, I'm linking those with a variable determined by a user selection(s) at runtime. I know I can add 'use strict', but we still have customers on IE8/9. I'm not 100% sure if that would cause problems. Correct me if I'm wrong, but I would have to create an object for every item if I didn't use a constructor correct? — Andrew L.
– Andrew L., Commented Dec 4, 2015 at 19:45
You can't link a property to a variable passed into a function as an argument anyway, there are not one but two places where all link to the variable has been lost, as JavaScript is purely pass-by-value. So when you call the function, the value of the variable (not a reference to the variable) is passed. Then when you assign that to a property, the value gets assigned, not a link to the argument or variable it came from. Strict mode has nothing to do with this. — T.J. Crowder
– T.J. Crowder, Commented Dec 4, 2015 at 20:12

spozun · Accepted Answer · 2015-12-04 18:21:09Z

1

I prefer the first answer, just change the second line from:

itemObject = {

to

return {

and then you can say:

var item1 = objFunction('item1Name');

In other words:

function objFunction (itemName) {
    return {'name' : itemName};
}

var y = objFunction("theName");
console.log(y.name);

edited Dec 4, 2015 at 18:21

answered Dec 4, 2015 at 18:13

spozun

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1 Comment

Andrew L. Over a year ago

Thank you! That works perfect. I don't necessarily need the second option. Now i can use these objects much more easily and simplify the code.

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