Question

I am new to javascript and for practice, I am using javascript to stripe even rows for tables with a particular class. Besides that, I am trying to create a ‘hover’ effect on table rows using javascript only.

I was able to create the onmouseover effect, however, I am having a very difficult time going back to the default style onmouseout of the table row.

Please keep in mind that I know this can easily be achieved with css or JQuery; however, for this, I would like to stick to javscript only.

What I tried:

    function alternate(){
        var tables = document.getElementsByTagName("table");     

        //apply the code to ALL tables on the page with a particular class
        for (var ti = 0; ti < tables.length; ++ti) {
            if (tables[ti].className == "striped"){ //stripe tables
                var rows = tables[ti].getElementsByTagName("tr");   
                for(i = 0; i < rows.length; i++){           
                    //change style of even rows to create striped effect
                    if(i % 2 == 0){ 
                        rows[i].className += "even"; //stripe even rows while maintaining default style to odd rows
                    }
                    rows[i].onmouseover = function() {
                        this.className="";
                        this.className="hovered";
                    }
                    rows[i].onmouseout = function() { 
                        if(i % 2 == 0){
                            this.className="even";
                        }else{
                            this.className="odd";
                        }                       
                    }
                }       
            }
        }
    }

Answer 1

I’m not sure if I quite understood your question, but I have created a jsfiddle which does what I think you meant.

The problem, from what I could tell, was that when row[i].mouseout is triggered, the value of i is the number of tables rows in your table. The fix is, to save the original classname on mouseover, and then re-assign that classname onmouseout. Here is the fiddle. http://jsfiddle.net/LBaZu/4/

function alternate() {
    var tables = document.getElementsByTagName("table");
    for (var ti = 0; ti < tables.length; ++ti) {
        if (tables[ti].className == "striped") {
            var rows = tables[ti].getElementsByTagName("tr");
            var cls; // Variable to save the className
            for (var i = 0; i < rows.length; i++) {
                if (i % 2 == 0) rows[i].className = "even";
                rows[i].onmouseover = function() {
                    cls = this.className;  // Assign the className here
                    this.className = "hovered";
                }
                rows[i].onmouseout = function() {
                    this.className = (cls == 'even') ? cls : 'odd';
                }
            }
        }
    }
}

Edit: I re-read your question and it occurred to me that you only wanted to set the odd table rows classname to odd on mouseout, not before.