Adding Properties and Methods to Objects using Prototypes in JavaScript

<span class="pln">
</span><span class="kwd">function</span><span class="pln"> </span><span class="typ">Animal</span><span class="pun">(</span><span class="pln">type</span><span class="pun">,</span><span class="pln"> legs</span><span class="pun">,</span><span class="pln"> sound</span><span class="pun">)</span><span class="pln"> </span><span class="pun">{</span><span class="pln">
    </span><span class="kwd">this</span><span class="pun">.</span><span class="pln">animalType </span><span class="pun">=</span><span class="pln"> type</span><span class="pun">;</span><span class="pln">
    </span><span class="kwd">this</span><span class="pun">.</span><span class="pln">numberOfLegs </span><span class="pun">=</span><span class="pln"> legs</span><span class="pun">;</span><span class="pln">
    </span><span class="kwd">this</span><span class="pun">.</span><span class="pln">sound </span><span class="pun">=</span><span class="pln"> sound</span><span class="pun">;</span><span class="pln">
    </span><span class="kwd">this</span><span class="pun">.</span><span class="pln">isPet </span><span class="pun">=</span><span class="pln"> </span><span class="kwd">false</span><span class="pun">;</span><span class="pln">
</span><span class="pun">}</span><span class="pln">

</span><span class="com">// Creating instances of the Animal constructor</span><span class="pln">
</span><span class="kwd">var</span><span class="pln"> dog </span><span class="pun">=</span><span class="pln"> </span><span class="kwd">new</span><span class="pln"> </span><span class="typ">Animal</span><span class="pun">(</span><span class="str">'Dog'</span><span class="pun">,</span><span class="pln"> </span><span class="lit">4</span><span class="pun">,</span><span class="pln"> </span><span class="str">'Bark'</span><span class="pun">);</span><span class="pln">
</span><span class="kwd">var</span><span class="pln"> cat </span><span class="pun">=</span><span class="pln"> </span><span class="kwd">new</span><span class="pln"> </span><span class="typ">Animal</span><span class="pun">(</span><span class="str">'Cat'</span><span class="pun">,</span><span class="pln"> </span><span class="lit">4</span><span class="pun">,</span><span class="pln"> </span><span class="str">'Meow'</span><span class="pun">);</span><span class="pln">
</span><span class="kwd">var</span><span class="pln"> parrot </span><span class="pun">=</span><span class="pln"> </span><span class="kwd">new</span><span class="pln"> </span><span class="typ">Animal</span><span class="pun">(</span><span class="str">'Parrot'</span><span class="pun">,</span><span class="pln"> </span><span class="lit">2</span><span class="pun">,</span><span class="pln"> </span><span class="str">'Squawk'</span><span class="pun">);</span><span class="pln">

</span><span class="typ">Animal</span><span class="pun">.</span><span class="pln">prototype</span><span class="pun">.</span><span class="pln">nameOfAnimal </span><span class="pun">=</span><span class="pln"> </span><span class="str">"My pet"</span><span class="pun">;</span><span class="pln">

</span><span class="typ">Animal</span><span class="pun">.</span><span class="pln">prototype</span><span class="pun">.</span><span class="pln">makeSound </span><span class="pun">=</span><span class="pln"> </span><span class="kwd">function</span><span class="pun">()</span><span class="pln"> </span><span class="pun">{</span><span class="pln">
    console</span><span class="pun">.</span><span class="pln">log</span><span class="pun">(</span><span class="kwd">this</span><span class="pun">.</span><span class="pln">sound</span><span class="pun">);</span><span class="pln">
</span><span class="pun">};</span><span class="pln">

dog</span><span class="pun">.</span><span class="pln">makeSound</span><span class="pun">();</span><span class="pln">
cat</span><span class="pun">.</span><span class="pln">makeSound</span><span class="pun">();</span><span class="pln">
parrot</span><span class="pun">.</span><span class="pln">makeSound</span><span class="pun">();</span><span class="pln">

</span><span class="com">// console.log(dog.nameOfAnimal);</span><span class="pln">
</span><span class="com">// console.log(cat.nameOfAnimal);</span><span class="pln">
</span><span class="com">// console.log(parrot.nameOfAnimal);</span><span class="pln">
</span><span class="com">// console.log(dog.isPet);</span><span class="pln">
</span><span class="com">// console.log(cat.isPet);</span><span class="pln">
</span><span class="com">// console.log(parrot.numberOfLegs);</span><span class="pln">

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