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POhow to have Javascript Object creation pattern with Reusable methods and private properties?
 

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  1. POhow to have Javascript Object creation pattern with Reusable methods and private properties?
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    <p>Considering object creation patterns with private properties, one way to do is :</p> <pre><code>function MyStack (){ var list = [], index = 0; this.push = function(val){ return list[index++] = val; }; this.pop = function(){// ...} } var stack1 = new MyStack(); stack1.push(5); var stack2 = new MyStack(); stack2.push(11); </code></pre> <p>Problem with this: Every instance of Stack has it's own copy of methods 'push' and 'pop'.</p> <p>Another way for implementing constructor method is:</p> <pre><code>function MyStack(){ this.list = []; this.index = 0; } MyStack.prototype = { insert: function(val){ return this.list[this.index++] = val; }, pop:function(){//...} } </code></pre> <p>Problem here: We lose the privacy of list and index.</p> <p>Is there a way, such that we can have both methods reuse among instances and privacy of properties ?</p> <p>I understand that we can have this for methods that don't operate on any state of the object, but I am talking more about those methods that do operate on the state.</p>
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    1. COYou could give each instance a random ID and store its private properties in some kind of data structure. But I would suggest to just forget about privat properties if you use constructor functions. JavaScript is not built for that and any workaround has some disadvantage.
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      1. USFelix Kling
    2. CO@FelixKling so lets say we have an auxiliary DS, Like {id1: { list:[3,4],currentIndex:2}, id2: { list:[2,1,4], currentIndex:3} } ... even then in the MyStack.prototype.insert = function(val){ currState = this.auxiliaryDS[this.id]; this.currState.list.push(val).. Again, it is not really private.
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    3. COYou could define the data store and the constructor function inside a function and only expose the constructor function. The data store would then be private and not be accessible from the outside. Yes, the ID would be accessible, but you could even generate a random property name for this if you wanted to obfuscate it. As I said, JS is not built for this and anything you do will be hacky and/or complex. Proper documentation is more valuable IMO. You can find quite a few related questions here: http://stackoverflow.com/search?q=javascript+private+instance+variables+and+prototype+methods
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