It's up to the user whether they want to use new tabs or new windows, it isn't the business of the developer to modify this behaviour. I do not think you can do it.
Pet peeve of mine - I hate it when sites force me to open in a new window / tab - I am quite capable of making that decision for myself. Particularly when they do it in javascript - that is really unhelpful.
You can, in Firefox it works, add the attribute target="_newtab" to the anchor to force the opening of a new tab.
<a href="some url" target="_newtab">content of the anchor</a>
In javascript you can use
window.open('page.html','_newtab');
Said that, I partially agree with Sam. You shouldn't force user to open new pages or new tab without showing them a hint on what is going to happen before they click on the link.
Let me know if it works on other browser too (I don't have a chance to try it on other browser than Firefox at the moment).
You can't directly control this, because it's an option controlled by Internet Explorer users.
Opening pages using Window.open with a different window name will open in a new browser window like a popup, OR open in a new tab, if the user configured the browser to do so.
All you are doing is telling the browser to open a new window NAMED "_newtab" and load page.html into it. Every new page you load will load into that window. However, if a user has their browser set to open new pages in new tabs instead of new windows, it will open a tab. Regardless, it's using the same name for the window or tab.
If you want different pages to open in different windows or tabs you will have to change the NAME of the new window/tab to something different such as:
window.open('page2.html', '_newtab2');
Of course the name for the new window/tab could be any name like page1, page2, page3, etc. instead of _newtab2.
This may work if you can call a batch file (I use php with
XP sp2 and IE8... you can try IE7, dunno). Use the following (or similar) in your .bat file to open Windows:
Start ""C:\Progra~1\Intern~1\iexplore "http://www.site.com". There is no space between the quotation mark and C:\Progr... etc. At some point, this may begin to open new windows (i.e., target="_blank") rather than new tabs, but works up to a point; not extensively tested. To use this in a regular batch file (CMD.exe), you probably need to have a window already open. Just sharing something I stumbled across. EDITED for clarification.