javascript detect # in url

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+6 Q:

javascript detect # in url

My application is an iframe app so when the user changes page they do not automatically get taken to the top. To combat this on page load I call

window.location.hash = 'tophash'

I have found however on some rare cases I need to take the user to a specific part of the page. So I make a url with #anotherID on the end. Problem is currently they are taken to tophash on page load.

What I need is if there is a hash within the url it does not run window.location.hash = 'tophash'

So my question is... how do I detech the presence of a # in the url?

+3 A:

Querying the hash property before setting it should do the job.

if ((!window.location.hash) || (window.location.hash == "#"))
 window.location.hash = "tophash";

Pekka 2010-09-12 14:59:24

It's not `== null` when it's empty, at least not on Chrome (http://jsbin.com/ecela4). It *should* be an empty string (and is on Chrome: http://jsbin.com/ecela4/2), but I'd probably code defensively and go with `== ""`.

T.J. Crowder 2010-09-12 15:03:09

hmmm == null did not work == '' did however

Starlin 2010-09-12 15:04:37

@T.J. good point! Changed to a `length` check and added a check for a lone `#` just to make sure - Chrome takes away lone `#`es but I wouldn't trust everyone does

Pekka 2010-09-12 15:05:12

@Starlin argh, my update was humbug, sorry. Please use the one posted now

Pekka 2010-09-12 15:10:40

!window.location.hash is a better way of checking hash, notice the ! Empty string, array, 0, undefined and null will all evaluate to false when using !

BGerrissen 2010-09-12 15:12:59

@BGerrissen fair point! Wasn't aware `!` was this flexible in JS. Changed.

Pekka 2010-09-12 15:16:08

@BGerrissen - That's not quite accurate. They will technically evaluate to `true` when using `!` because they are all "falsey". I imagine that's what you meant. (Except that *empty array* is not "falsey" like the rest).

patrick dw 2010-09-12 15:40:46

I stand corrected, rather meant 'evaluate to boolean' and yeh, empty array doesn't evaluate to false.

BGerrissen 2010-09-12 16:56:48

ansaurus

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javascript detect # in url

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