Javascript if variable is not null

Question

if (typeof (location.x != null) {

Using the above I run into the follow error: Uncaught TypeError: Cannot read property 'x' of null

I have tried console.log(location.x) which results in an example with null

using location tends to be a bad variable name because of window.location. One miss var and your "truthy" check will be true. — epascarello
– epascarello, Commented Sep 24, 2014 at 14:15
@epascarello—then why is it null? BTW, typeof always returns a string which is never == null. — RobG
– RobG, Commented Sep 24, 2014 at 14:16
@RobG: window.location and the local variable location, in this context, are different. Your confusion is precisely the reason for epascarello's comment. — MobA11y
– MobA11y, Commented Sep 24, 2014 at 14:18
@epascarello is 100% correct about the variable name being unwise, RobG makes a very important point (for the OP) about typeof returning a string. — Chris Baker
– Chris Baker, Commented Sep 24, 2014 at 17:03

Fabio · Accepted Answer · 2014-09-24 14:20:37Z

8

if (location && location.x) {

}

edited Sep 24, 2014 at 14:20

answered Sep 24, 2014 at 14:14

Fabio

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3 Comments

epascarello Over a year ago

hopefully x is not a falsey value.

Fabio Over a year ago

in this case you use location.x!=undefined for condition in if statement

Chris Baker Over a year ago

typeof myVariable !== 'undefined is safer IMO -- no terrorist jQuery plugin can redefine undefined on you if you use typeof.

tymeJV · Accepted Answer · 2014-09-24 14:13:39Z

2

You can just do:

if (location && location.x) {

}

answered Sep 24, 2014 at 14:13

tymeJV

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2 Comments

ngplayground Over a year ago

Still results with Uncaught TypeError: Cannot read property 'x' of null

epascarello Over a year ago

hopefully x is not a falsey value.

Sébastien P. · Accepted Answer · 2014-09-24 14:47:41Z

1

The x attribute can't be reached because your location variable is null

edited Sep 24, 2014 at 14:47

answered Sep 24, 2014 at 14:14

Sébastien P.

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