Javascript history go — if not, go to index.html

Question

To go back to the appropriate tumblr page, we're using:

<a href="javascript:history.go(-1)"> Back </a>

However, we're getting a lot of traffic directly from the twitter app, and this stops the function working. Is there a way so that if the history.go doesn't work (or takes you outside the site), it will just take you to index.html?

This is one of the pages the history button is on: http://lexican.info/post/49265445109/sesquipedalophobia

Thanks for any help at all.

Answer 1

Try to check how many page in the history list with history.length :

http://www.w3schools.com/jsref/prop_his_length.asp

Answer 2

可悲的是，我认为这是不可能的，因为帖子与帖子显示在索引的哪一页之间没有关系。