Question

I ran into the excellent jstree jQuery UI plug in this morning. In a word – great! It is easy to use, easy to style & does what it says on the box. The one thing I have not yet been able to figure out is this – in my app I want to ensure that only one node is expanded at any given time. i.e. when the user clicks on the + button and expands a node, any previously expanded node should silently be collapsed. I need to do this in part to prevent the container div for a rather lengthy tree view from creating an ugly scrollbar on overflow and also to avoid “choice overload” for the user.

I imagine that there is some way of doing this but the good but rather terse jstree documentation has not helped me to identify the right way to do this. I would much appreciate any help.

Answer 1

jsTree is great but its documentation is rather dense. I eventually figured it out so here is the solution for anyone running into this thread.

Firstly, you need to bind the open_node event to the tree in question. Something along the lines of

$("tree").jstree({"themes":objTheme,"plugins":arrPlugins,"core":objCore}).
bind("open_node.jstree",function(event,data){closeOld(data)}); 

i.e. you configure the treeview instance and then bind the open_node event. Here I am calling the closeOld function to do the job I require – close any other node that might be open. The function goes like so

function closeOld(data)
{
    var nn = data.rslt.obj;
    var thisLvl = nn;
    var levels = new Array();
    var iex = 0;
    while (-1 != thisLvl)
    {
        levels.push(thisLvl);
        thisLvl = data.inst._get_parent(thisLvl);
        iex++;
    }

    if (0 < ignoreExp)
    {
        ignoreExp--;
        return;
    }

    $("#divElements").jstree("close_all");
    ignoreExp = iex;
    var len = levels.length - 1;
    for (var i=len;i >=0;i--) $('#divElements').jstree('open_node',levels[i]);
}

This will correctly handle the folding of all other nodes irrespective of the nesting level of the node that has just been expanded.

A brief explanation of the steps involved

• First we step back up the treeview until we reach a top level node (-1 in jstree speak) making sure that we record every ancestor node encountered in the process in the array levels
• Next we collapse all the nodes in the treeview
• We are now going to re-expand all of the nodees in the levels array. Whilst doing so we do not want this code to execute again. To stop that from happening we set the global ignoreEx variable to the number of nodes in levels
• Finally, we step through the nodes in levels and expand each one of them