selectorStr = this;
allCbId = checkAllId;
$(selectorStr).bind("click", handleClick);
if (allCbId != null) {
$(allCbId).bind("click", handleAllClick);
}

};

function handleAllClick(event) {
var checkStatus = this.checked; // set all the checkboxes as selected
$(selectorStr).each(function() {
this.checked = checkStatus;
})
}

function handleClick(event) {
var val = this.value;
var checkStatus = this.checked;
var allChecked = checkStatus;
//get the checkbox number which the user has checked

//check whether user has pressed shift
if (event.shiftKey) {
if (prevChecked != 'null') {
//get the current checkbox number
var ind = 0, found = 0, currentChecked;
currentChecked = getSelected(val);

ind = 0;

$(selectorStr).each(function(i) {

if (currentChecked = currentChecked && ind = prevChecked && ind <= currentChecked) {
this.checked = checkStatus;
}
}
ind++;
allChecked = allChecked && this.checked;
});

prevChecked = currentChecked;

}
} else {
if (checkStatus) {
prevChecked = getSelected(val);

}
$(selectorStr).each(function() {
allChecked = allChecked && this.checked;
});
}
if (allCbId != null) {
$(allCbId).attr("checked", allChecked); // set "all" checkbox to checked
}
};

function getSelected(val) {
var ind = 0, found = 0, checkedIndex;

$(selectorStr).each(function(i) {
if (val == this.value && found != 1) {
checkedIndex = ind;
return false; // break loop
}
ind++;
return true;
});