in the column header property of the view column called "check box"  If you select it a check box will appear in the column header that allows you to select all the documents.

Paul,

yes I know that feature...

but i need to click a button and run some SSJS on all the listed documents.

Use a client side js to check the checkboxes on screen before your SSJS runs.  You can adapt the code from here:

http://stackoverflow.com/questions/386281/how-to-implement-select-all-check-box-in-html

If you have the document collection on the screen that you want to process and it's "all" of them why do you need to select them first?

Seems an un-neccessary step.

You can use the column header api to select them all in ssjs as well as the mentions csjs if that is a requirement.