Randomizer //JavaScript Repository

Description

Container able to return itens based on probability, randomized and sequentially.
Created: 2005.08.08

Code (Download)

//+ Jonas Raoni Soares Silva
//@ http://jsfromhell.com/classes/randomizer [rev. #1]

Randomizer = function(type){
    var o = this;
    (o.d = [], o.t = type || Randomizer.RANDOMIZED, o.x = -1, o.u = 0);
};
with({o: Randomizer, p: Randomizer.prototype}){
    o.SEQUENCED = (o.PROBABILITY = (o.RANDOMIZED = 0) + 1) + 1;
    p.add = function(object, probability){
        this.u += (this.d[ this.d.length ] = {o: object, p: Math.abs(probability || 1)}).p;
    };
    p.remove = function(index){
        index > -1 && index < this.d.length && (this.u -= this.d.splice(index, 1).p);
    };
    p.next = function(){
        if(!this.u)
            return null;
        var i = 0, m = 0, x = this.t == Randomizer.SEQUENCED ?
            (this.x = (this.x + 1) % this.d.length)
            : Math.round(Math.random() * (this.t == Randomizer.PROBABILITY ? this.u
            : this.d.length - 1));
        if(this.t == Randomizer.PROBABILITY)
            do m += this.d[ i++ ].p;
            while(x > m || !((x = --i) + 1));
        return this.d[ x ].o;
    };
}

Example (Example)

<script type="text/javascript">
//<![CDATA[

var probability = new Randomizer(Randomizer.PROBABILITY);
probability.add("A", 20);
probability.add("B", 10);
probability.add("C", 2);

document.write("<h2>Randomizer.PROBABILITY = A: 20, B: 10, C: 2</h2>");
for(var i = 20; i--; document.write(probability.next(), ", "));

var random = new Randomizer(Randomizer.RANDOMIZED);
random.add("A");
random.add("B");
random.add("C");

document.write("<h2>Randomizer.RANDOMIZED = A, B, C</h2>");
for(var i = 20; i--; document.write(random.next(), ", "));


var sequenced = new Randomizer(Randomizer.SEQUENCED);
sequenced.add("A");
sequenced.add("B");
sequenced.add("C");

document.write("<h2>Randomizer.SEQUENCED = A, B, C</h2>");
for(var i = 20; i--; document.write(sequenced.next(), ", "));

//]]>
</script>

Help

Constructor

Randomizer(type: RandomizerType)

Generates an instance of Randomizer.

type: adjusts the container behaviour, the possible values are: Randomizer.SEQUENCED (returns items in the same order they were inserted), Randomizer.PROBABILITY (returns items randomically, but taking in consideration the probability defined for each one) and Randomizer.RANDOMIZED (returns items randomically)

Methods

Randomizer.add(object: Object, probability: Integer): void

Adds an item to the container.

object: object that will be added
probability: useful only when the container type is "Randomizer.PROBABILITY", where "probability" must be an integer number positive and higher than 1

Randomizer.remove(index: Integer): void

Removes an element from the container.

index: index of the element

Randomizer.next(void): Object

Returns an item based on the container type.

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