.row.auto-clearfix in javascript In Twitter Bootstrap fmk add .clearfix elements to automatically finish row. Usage: Put a .auto-clearfix css class on a .row element. Call this stuff after resize, on load, put it in a function, etc...

.row.auto-clearfix.js

$(".row.auto-clearfix").each(function(){
    $(this).find(".created-by-auto-clearfix").remove(); //start cleaning previous stuff
    var prevPos=0;
    $(this).find(">[class^='col-'],>[class^='span']").each(function(){
        var thisPos=$(this).position().left;
        if(thisPos!=0 && thisPos==prevPos){ //this element should be on a new line dude!
            $(this).before($("<div class='clearfix created-by-auto-clearfix'>"));
        }
        prevPos=$(this).position().left;
    })
});