How to check if a Javascript variable is defined before invoking it

Question

I am using Cordova GA plugin to track events, but when testing in my browser I keep getting:

ReferenceError: plugin is not defined

I tried many ways to check if the plugin has been defined, but it still throws this error. How can I properly check if the plugin has been defined before I invoke the function?

Btw take a look at this emulate.phonegap.com

Fabio Filippi
– Fabio Filippi

2014-12-22 08:26:15 +00:00
Commented Dec 22, 2014 at 8:26 — Fabio Filippi
– Fabio Filippi, Commented Dec 22, 2014 at 8:26

Andreas Argelius · Accepted Answer · 2014-12-22 08:22:17Z

5

To check if a JavaScript variable is undefined you can use

if (typeof myVariable === 'undefined') {
  console.log('The variable is undefined.');
}

answered Dec 22, 2014 at 8:22

Andreas Argelius

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Comments

score 1 · Accepted Answer · 2014-12-22 08:29:36Z

1

You may simply put a check before running your code:

if (window.plugin) {//I had assume that `plugin` is in global scope
  alert('plugin');
} else {
  alert('no plugin');
}

Using typeof

if('undefined' === typeof plugin) {
  alert('no plugin');
} else {
  alert('plugin ...');
}

edited Dec 22, 2014 at 8:29

answered Dec 22, 2014 at 8:23

user2575725

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