defining multiple variables with one `var` keyword in javascript [duplicate]

Question

I have a line in my source code written by someone else:

var campaignLimits = 10, campaignsArray = new Array();

I just wanted to know, whether campaignsArray here becomes global variable, or the var applies to campaignsArray as well?

var campaignLimits = 10, campaignsArray = new Array(); is the same as var campaignLimits = 10; var campaignsArray = new Array();. Whether they're global or not will depend on the scope where they're defined. — phoa
– phoa, Commented Nov 30, 2016 at 8:28
the second one. for testing you can put it in a function and console.log that variable outside of that function. — marmeladze
– marmeladze, Commented Nov 30, 2016 at 8:29
var applies to campaignsArray as well. It's supported by Douglas Crockford, you may find some articles on this choice : sixrevisions.com/javascript/single-var-pattern and its critic danhough.com/blog/single-var-pattern-rant — lkostka
– lkostka, Commented Nov 30, 2016 at 8:29
Both campaignLimits and campaignArrays become a variable within a current scope. If you declare it in a global scope, they will both become global variables. — Yeldar Kurmangaliyev
– Yeldar Kurmangaliyev, Commented Nov 30, 2016 at 8:29

Sharath Bangera · Accepted Answer · 2016-11-30 08:31:51Z

0

Assuming you have not used any programming pattern, If its written inside a function then its not global.

(function() { var campaignLimits = 10, campaignsArray = new Array(); })();

as @phoa commented it is same as

(function() { var campaignLimits = 10; var campaignsArray = new Array(); })();

Try it in your console and see whether you will be able to access campaignsArray.

answered Nov 30, 2016 at 8:31

Sharath Bangera

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1 Comment

What do you mean by "assuming you have not used any programming pattern"?