Introduction

This article is about Priority Scenario implementation in JavaScript.

Background

ASP.NET knowledge.

Using the code

You have to simply add this script block into the header section of the page.

Do not make any modifications to the code. It works as expected.

You can still try to put your knowledge to test.. But believe me it will work in the fashion I have designed.

<script language="javascript" type="text/javascript">
    <!--
    var selects = null, assignments = null, currentDDL = null, currentValue = null, priorityDDls = null;

    function PriorityDDList_onchange() {
        ddl = window.event.srcElement;
        removeEvents();
        newValue = parseToNumber(ddl.value);
        if (newValue > 0 && currentValue > 0) {
            synchAssignments();
            assignments[1][currentValue - 1] = newValue;
            if (newValue > currentValue) {
                for (var i = newValue; i > currentValue; i--) {
                    assignments[1][i - 1] = i - 1;
                }
            }
            else if (newValue < currentValue) {
                for (var i = newValue; i < currentValue; i++) {
                    assignments[1][i - 1] = i + 1;
                }
            }
            applyAssignments();
        }
        else if (currentValue == 0) {
            var newValueDDL = null;
            for (var i = 0; !newValueDDL && i < priorityDDls.length; i++)
                newValueDDL = priorityDDls[i] != currentDDL && 
                   parseToNumber(priorityDDls[i].value) == newValue ? priorityDDls[i] : null;
            if (newValueDDL)
                newValueDDL.value = currentValue;
        }
        attacEvents();
    }

    function PriorityDDList_onclick() {
        currentValue = parseToNumber((currentDDL = window.event.srcElement).value);
    }

    function parseToNumber(str) {
        return isNaN(str) ? 0 : parseInt(str);
    }

    function init() {
        attacEvents();
        initAssignments();
    }

    function initAssignments() {
        assignments = new Array();
        assignments.push(new Array());
        assignments.push(new Array());
        for (var i = 1; i <= priorityDDls.length; i++) {
            assignments[0][i - 1] = i;
            assignments[1][i - 1] = i;
        }
    }

    function synchAssignments() {
        for (var i = 1; i <= priorityDDls.length; i++) {
            assignments[1][i - 1] = (assignments[0][i - 1] = i);
        }
    }

    function applyAssignments() {
        for (var i = 0; i < priorityDDls.length; i++) {
            priorityDDls[i].value = priorityDDls[i] != currentDDL && 
               (index = parseToNumber(priorityDDls[i].value)) ? 
                assignments[1][index - 1].toString() : priorityDDls[i].value;
        }
    }

    function attacEvents() {
        selects = document.getElementsByTagName("select");
        priorityDDls = new Array();
        for (var i = 0; i < selects.length; i++) {
            if (selects[i].id.indexOf("ddlAP") > -1) {
                selects[i].onchange = PriorityDDList_onchange;
                selects[i].onclick = PriorityDDList_onclick;
                priorityDDls.push(selects[i]);
            }
        }
    }

    function removeEvents() {
        for (var i = 0; i < selects.length; i++) {
            if (selects[i].id.indexOf("ddlAP") > -1) {
                selects[i].onchange = null;
                selects[i].onclick = null;
            }
        }
        selects = null;
    }
-->
</script>