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Singleton code example simplification #176

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Singleton code example simplification #176

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23 changes: 3 additions & 20 deletions book/index.html
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Original file line number Diff line number Diff line change
Expand Up @@ -1512,20 +1512,14 @@ <h2 id="singletonpatternjavascript">

var privateVariable = "Im also private";

var privateRandomNumber = Math.random();

return {

// Public methods and variables
publicMethod: function () {
console.log( "The public can see me!" );
},

publicProperty: "I am also public",

getRandomNumber: function() {
return privateRandomNumber;
}
publicProperty: "I am also public"

};

Expand Down Expand Up @@ -1557,14 +1551,8 @@ <h2 id="singletonpatternjavascript">

// Singleton

var privateRandomNumber = Math.random();

return {

getRandomNumber: function() {
return privateRandomNumber;
}

};

};
Expand All @@ -1588,16 +1576,11 @@ <h2 id="singletonpatternjavascript">

var singleA = mySingleton.getInstance();
var singleB = mySingleton.getInstance();
console.log( singleA.getRandomNumber() === singleB.getRandomNumber() ); // true
console.log( singleA === singleB ); // true

var badSingleA = myBadSingleton.getInstance();
var badSingleB = myBadSingleton.getInstance();
console.log( badSingleA.getRandomNumber() !== badSingleB.getRandomNumber() ); // true

// Note: as we are working with random numbers, there is a
// mathematical possibility both numbers will be the same,
// however unlikely. The above example should otherwise still
// be valid.
console.log( badSingleA !== badSingleB ); // true
</pre>

<p>What makes the Singleton is the global access to the instance (generally through <code>MySingleton.getInstance()</code>) as we don't (at least in static languages) call <code>new MySingleton()</code> directly. This is however possible in JavaScript.</p>
Expand Down