Can you use a variable value to specify a jquery object name?

Question

I have:

if (!myObj.login_id) { 
    alert("The object for login_id does not exist.");
} else {
    alert("The object for login_id DOES exist. The value of the object is: " + myObj.login_id);
}

This is working properly. The object and it's value are defined already. However, I have multiple objects which are named after their ID attr. So, I try doing this (say for example this is a click event:

objtitle = $(this).attr('id'); // this is "login_id"

if (!myObj.objtitle) {
    alert("The object for "+objtitle+" does not exist.");   
} else {
    alert("The object for "+objtitle+" DOES exist. The value of the object is: " + myObj.objtitle);
}

Why does it stop working when I use a variable for the name of the object?

if ( !myObj[ this.id ] ) { ...

Šime Vidas
– Šime Vidas

2011-10-03 15:31:25 +00:00
Commented Oct 3, 2011 at 15:31 — Šime Vidas
– Šime Vidas, Commented Oct 3, 2011 at 15:31

Daniel A. White · Accepted Answer · 2011-10-03 15:31:01Z

10

Use square brackets.

myObj[objtitle]

answered Oct 3, 2011 at 15:31

Daniel A. White

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1 Comment

Oseer Over a year ago

Just seeing how I can thank someone for helping me out on here. I clicked "this information is useful" and "this is your accepted answer"... thanks also to lonesomeday!

lonesomeday · Accepted Answer · 2011-10-03 15:33:20Z

4

There are two ways of accessing an object's properties: the dot syntax and the square bracket syntax. These are called member operators. So the following two are equivalent:

obj.foo
obj['foo']

The dot syntax (the first one) is a literal name. obj.objtitle therefore attempts to find a property called objtitle. If you have a variable containing the property name you want, you have to use the square bracket syntax.

myObj[objtitle]

answered Oct 3, 2011 at 15:33

lonesomeday

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