set global var using jquery and dynamic variable name

Question

I am trying to set a javascript global var using jquery and dynamic variable names like this:

var home_phone_number // located outside of any functions
.
.
.
function setPhoneVars(phone){
// do stuff here to determine the correct prefix
thePrefix = 'home_phone_'
$(thePrefix + "number").val(phone.number);

}

When I do this, the value of home_phone_number is undefined.

But, when I set the phone number manually, like this:

home_phone_number = phone.number

the variable is set as expected.

why do i think it would work? I can directly assign the value from within the javascript function WITHOUT using jquery, that's why. — Jack Albright
– Jack Albright, Commented Oct 22, 2012 at 19:43
jQuery is a library, a collection of functions and It simply doesn't have a function (as far as I know) to set the value of a variable. $(thePrefix + "number") Will look for an HTML element like <home_phone_number> — Selvakumar Arumugam
– Selvakumar Arumugam, Commented Oct 22, 2012 at 19:53

Niet the Dark Absol · Accepted Answer · 2012-10-22 19:41:22Z

12

Global variables are properties of the window object, so can be accessed as such:

window[thePrefix+'number'] = phone.number;

answered Oct 22, 2012 at 19:41

Niet the Dark Absol

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3 Comments

Jack Albright Over a year ago

that worked. Thanks. But still I wonder why the jQuery code did not, and is there a syntax change I could have made to make it work?

Niet the Dark Absol Over a year ago

Because the jQuery code makes bugger all sense, that's why it didn't work.

Jack Albright Over a year ago

bugger all sense. I like that.

VisioN · Accepted Answer · 2012-10-22 19:41:44Z

1

You can access global variables through window object, e.g.

var home_phone_number = "value";

function setPhoneVars(phone) {
    var thePrefix = "home_phone_";
    window[thePrefix + "number"] = phone.number;
}

answered Oct 22, 2012 at 19:41

VisioN

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Comments

Sushanth -- · Accepted Answer · 2012-10-22 19:43:19Z

1

Instead of having such many globals.. you can use a single object..

var globals = {
   home_phone_number: 0 // located outside of any functions
} 


function setPhoneVars(phone){
  // do stuff here to determine the correct prefix
  thePrefix = 'home_phone_'
  globals[thePrefix + "number"] = phone.number;
}

edited Oct 22, 2012 at 19:43

Sushanth --

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answered Oct 22, 2012 at 19:42

Selvakumar Arumugam

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2 Comments

Niet the Dark Absol Over a year ago

Technically, by using global variables, you already are using a single object: window.

Selvakumar Arumugam Over a year ago

@Kolink True, I understand the above is additional wrapper.. but this I believe is is more like inside a group.. Something like window.pluginA.property and window.pluginB.property

Oliver Gray · Accepted Answer · 2012-10-22 19:53:18Z

0

I think your use of JQuery is not appropriate; .val() is intended to set the value of HTML elements, i.e. HTML objects in the DOM.

To simply set a dynamic JavaScript variable you could use eval() which is a JavaScript function which treats a string as executable code;

thePrefix = "home_phone_";
eval(thePrefix + "number = phone.number;");

answered Oct 22, 2012 at 19:53

Oliver Gray

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