Question

see fiddle

i have html table and one textbox and one button.make cell selection by dragging on cell .on click of button i am getting value of textbox and put into span tag of cell. i have to disble click on minute cell 0,15,30,45. In fiddle u see when i click on minute cell then it makes css green and css length is incremented (those chking in alert).

Answer 1

Is this what you want ?

–EDITED–

Now you can only highlight in a straight way (up or down).
Probably there is a more elegant way to do all of this but i think this will works as you want

DEMO: http://jsfiddle.net/vrW2n/9/

// Add this variable    
var lastRow = 0;

In mousedown():

    // This line gets the index of the first clicked row.
    lastRow = $(this).closest("tr")[0].rowIndex;

    active = true;
    $(".csstdhighlight").removeClass("csstdhighlight"); // clear previous selection

    //This is the big trick
    $(".temp_selected").removeClass("temp_selected");
...

And in mousemove():

...
    /* Begin my edit
    Compares the actual 'mousemove' row index
    with the last and next row index
    */
    var thisRow = $(this).closest("tr")[0].rowIndex;

    if( lastRow == thisRow || lastRow == thisRow - 1 || lastRow == thisRow + 1 ){
        lastRow = $(this).closest("tr")[0].rowIndex;
    }else
        return;
    // End my edit
...