How to access a dynamic property: objectName.{variable}

Question

i need to access

objectName.myID 

but the "myID" part is dynamically generated..

how do i do this?

i tried

this['objectName.'+ variable]

i'd hate to use eval...

ps this happens in a function (local scope) by the way..

Answer 1

You can access Object properties in two ways:

o.propertyname
//or
o.["propertyname"]

When using the bracket notation you have to put the propertyname in quotes or else it will be interpreted as a variable name (which in your case is exactly what you want). So in your case where you have stored the name of the property as a string, the way to go would be:

var variable = "propertyname";
o[variable];
/* /\ variable is replace with it's string representation "propertyname" */

You can even call methods this way:

var o = {};
var functionname = 'toString';
o[functionname]();

You can mix both notations, your example would look like:

var obj = 'objectName';
var prop = 'myID';
this[obj][prop]
// or this is possible too:
this.objectName[prop]

Answer 2

Assuming propertyName is the name of a variable holding the name of the property, for example 'myId', then you can use.

objectName[propertyName]

More details in the MDN : Working with objects