How do I show mouseover tooltip for header cell

Question

I am stuck with using Dojo, so I must do it in the dojo way for this...

So I have this table, with the first row being the header row, and I want users be able to put their mouse on the header cells and a tooltip message would pop out.

So far this is my code:

onHeaderCellMouseOver: function(e){
    if(e.cellNode){
        var column = filt_grid.structFlat[e.cellIndex];
        if (column) {
            dijit.showTooltip('hello world', e.cellNode, 'before');
        }
        dojo.addClass(e.cellNode, this.cellOverClass);
    }
},

onHeaderCellMouseOut: function(e){
    if(e.cellNode){
        dijit.hideTooltip(e.cellNode);
        dojo.removeClass(e.cellNode, this.cellOverClass);
    }
}

With this code, it doesn't show tooltips, and on the Chrome debug console, it showed error message:

Uncaught TypeError: Cannot read property 'charAt' of undefined

Does anyone know what happened? I never used CharAT for the mouse hover...

Answer 1

What is the 'before' doing there? Delete the 'before' and it will work.