kn9ts/ObserverDP.html

## ObserverDP.html
<html>

<head>
    <script language="javascript">
    function ArrayList() {
        this.aList = []; //initialize with an empty array
    }

    ArrayList.prototype.Count = function() {
        return this.aList.length;
    }

    ArrayList.prototype.Add = function(object) {
        return this.aList.push(object); //Object are placed at the end of the array
    }

    ArrayList.prototype.GetAt = function(index) //Index must be a number
        {
            if (index > -1 && index < this.aList.length)
                return this.aList[index];
            else
                return undefined; //Out of bound array, return undefined
        }

    ArrayList.prototype.Clear = function() {
        this.aList = [];
    }

    ArrayList.prototype.RemoveAt = function(index) // index must be a number
        {
            var m_count = this.aList.length;

            if (m_count > 0 && index > -1 && index < this.aList.length) {
                switch (index) {
                    case 0:
                        this.aList.shift();
                        break;
                    case m_count - 1:
                        this.aList.pop();
                        break;
                    default:
                        var head = this.aList.slice(0, index);
                        var tail = this.aList.slice(index + 1);
                        this.aList = head.concat(tail);
                        break;
                }
            }
        }

    ArrayList.prototype.Insert = function(object, index) {
        var m_count = this.aList.length;
        var m_returnValue = -1;

        if (index > -1 && index <= m_count) {
            switch (index) {
                case 0:
                    this.aList.unshift(object);
                    m_returnValue = 0;
                    break;
                case m_count:
                    this.aList.push(object);
                    m_returnValue = m_count;
                    break;
                default:
                    var head = this.aList.slice(0, index - 1);
                    var tail = this.aList.slice(index);
                    this.aList = this.aList.concat(tail.unshift(object));
                    m_returnValue = index;
                    break;
            }
        }

        return m_returnValue;
    }

    ArrayList.prototype.IndexOf = function(object, startIndex) {
        var m_count = this.aList.length;
        var m_returnValue = -1;

        if (startIndex > -1 && startIndex < m_count) {
            var i = startIndex;

            while (i < m_count) {
                if (this.aList[i] == object) {
                    m_returnValue = i;
                    break;
                }

                i++;
            }
        }

        return m_returnValue;
    }


    ArrayList.prototype.LastIndexOf = function(object, startIndex) {
        var m_count = this.aList.length;
        var m_returnValue = -1;

        if (startIndex > -1 && startIndex < m_count) {
            var i = m_count - 1;

            while (i >= startIndex) {
                if (this.aList[i] == object) {
                    m_returnValue = i;
                    break;
                }

                i--;
            }
        }

        return m_returnValue;
    }

    function Observer() {
        this.Update = function() {
            return;
        }
    }


    function Subject() {
        this.observers = new ArrayList();
    }

    Subject.prototype.Notify = function(context) {
        var m_count = this.observers.Count();

        for (var i = 0; i < m_count; i++)
            this.observers.GetAt(i).Update(context);
    }

    Subject.prototype.AddObserver = function(observer) {
        if (!observer.Update)
            throw 'Wrong parameter';

        this.observers.Add(observer);
    }

    Subject.prototype.RemoveObserver = function(observer) {
        if (!observer.Update)
            throw 'Wrong parameter';

        this.observers.RemoveAt(this.observers.IndexOf(observer, 0));
    }
    </script>
</head>

<body bgcolor="#ff9900">
    <table width="100%" border="0">
        <tr>
            <td align="center">
                <INPUT style="color: #ff9900" id="BtnAdd" onclick="AddObserver()" type="button" value='Insert a new "Observer" checkbox'>
            </td>
        </tr>
        <tr>
            <td align="center" width="100%">Observable/Subject
                <INPUT id="MainCheckBox" type="checkbox" name="MainCheckBox">Checkbox</td>
        </tr>
        <tr>
            <td align="center">
                <div id="MainContainer"></div>
            </td>
        </tr>
    </table>
    <script language="javascript">
    function inherits(base, extension) {
        for (var property in base) {
            try {
                extension[property] = base[property];
            } catch (warning) {}
        }
    }

    var cont = document.getElementById('MainContainer');

    var mainCheck = document.getElementById('MainCheckBox');

    inherits(new Subject(), mainCheck);

    mainCheck["onclick"] = new Function("mainCheck.Notify(mainCheck.checked)");


    function AddObserver() {
        var check = document.createElement("INPUT");
        check.type = 'checkbox';

        inherits(new Observer(), check)

        check.Update = function(value) {
            this.checked = value;
        }

        mainCheck.AddObserver(check);

        cont.appendChild(check);
    }
    </script>
</body>

</html>
	<html>

	<head>
	<script language="javascript">
	function ArrayList() {
	this.aList = []; //initialize with an empty array
	}

	ArrayList.prototype.Count = function() {
	return this.aList.length;
	}

	ArrayList.prototype.Add = function(object) {
	return this.aList.push(object); //Object are placed at the end of the array
	}

	ArrayList.prototype.GetAt = function(index) //Index must be a number
	{
	if (index > -1 && index < this.aList.length)
	return this.aList[index];
	else
	return undefined; //Out of bound array, return undefined
	}

	ArrayList.prototype.Clear = function() {
	this.aList = [];
	}

	ArrayList.prototype.RemoveAt = function(index) // index must be a number
	{
	var m_count = this.aList.length;

	if (m_count > 0 && index > -1 && index < this.aList.length) {
	switch (index) {
	case 0:
	this.aList.shift();
	break;
	case m_count - 1:
	this.aList.pop();
	break;
	default:
	var head = this.aList.slice(0, index);
	var tail = this.aList.slice(index + 1);
	this.aList = head.concat(tail);
	break;
	}
	}
	}

	ArrayList.prototype.Insert = function(object, index) {
	var m_count = this.aList.length;
	var m_returnValue = -1;

	if (index > -1 && index <= m_count) {
	switch (index) {
	case 0:
	this.aList.unshift(object);
	m_returnValue = 0;
	break;
	case m_count:
	this.aList.push(object);
	m_returnValue = m_count;
	break;
	default:
	var head = this.aList.slice(0, index - 1);
	var tail = this.aList.slice(index);
	this.aList = this.aList.concat(tail.unshift(object));
	m_returnValue = index;
	break;
	}
	}

	return m_returnValue;
	}

	ArrayList.prototype.IndexOf = function(object, startIndex) {
	var m_count = this.aList.length;
	var m_returnValue = -1;

	if (startIndex > -1 && startIndex < m_count) {
	var i = startIndex;

	while (i < m_count) {
	if (this.aList[i] == object) {
	m_returnValue = i;
	break;
	}

	i++;
	}
	}

	return m_returnValue;
	}


	ArrayList.prototype.LastIndexOf = function(object, startIndex) {
	var m_count = this.aList.length;
	var m_returnValue = -1;

	if (startIndex > -1 && startIndex < m_count) {
	var i = m_count - 1;

	while (i >= startIndex) {
	if (this.aList[i] == object) {
	m_returnValue = i;
	break;
	}

	i--;
	}
	}

	return m_returnValue;
	}

	function Observer() {
	this.Update = function() {
	return;
	}
	}


	function Subject() {
	this.observers = new ArrayList();
	}

	Subject.prototype.Notify = function(context) {
	var m_count = this.observers.Count();

	for (var i = 0; i < m_count; i++)
	this.observers.GetAt(i).Update(context);
	}

	Subject.prototype.AddObserver = function(observer) {
	if (!observer.Update)
	throw 'Wrong parameter';

	this.observers.Add(observer);
	}

	Subject.prototype.RemoveObserver = function(observer) {
	if (!observer.Update)
	throw 'Wrong parameter';

	this.observers.RemoveAt(this.observers.IndexOf(observer, 0));
	}
	</script>
	</head>

	<body bgcolor="#ff9900">
	<table width="100%" border="0">
	<tr>
	<td align="center">
	<INPUT style="color: #ff9900" id="BtnAdd" onclick="AddObserver()" type="button" value='Insert a new "Observer" checkbox'>
	</td>
	</tr>
	<tr>
	<td align="center" width="100%">Observable/Subject
	<INPUT id="MainCheckBox" type="checkbox" name="MainCheckBox">Checkbox</td>
	</tr>
	<tr>
	<td align="center">
	<div id="MainContainer"></div>
	</td>
	</tr>
	</table>
	<script language="javascript">
	function inherits(base, extension) {
	for (var property in base) {
	try {
	extension[property] = base[property];
	} catch (warning) {}
	}
	}

	var cont = document.getElementById('MainContainer');

	var mainCheck = document.getElementById('MainCheckBox');

	inherits(new Subject(), mainCheck);

	mainCheck["onclick"] = new Function("mainCheck.Notify(mainCheck.checked)");


	function AddObserver() {
	var check = document.createElement("INPUT");
	check.type = 'checkbox';

	inherits(new Observer(), check)

	check.Update = function(value) {
	this.checked = value;
	}

	mainCheck.AddObserver(check);

	cont.appendChild(check);
	}
	</script>
	</body>

	</html>