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Editorial Team
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Asked: 2026-05-20T19:43:25+00:00

<html> <head> <script type=text/javascript> function Person (name, age) { this.name = name; this.age =

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<html>
<head>

    <script type="text/javascript">

    function Person (name, age) {
        this.name = name;
        this.age = age;
        this.sayName = function () {
            alert(this.name);
        }
    }    
    var person1 = new Person ("tom", 29);
    var person2 = new Person ("frank", 21);
    alert(person1.sayName==person2.sayName);

    </script>
</head>

<body>
</body>
</html>
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1 Answer

  1. Editorial Team

    There is nothing wrong with it (other than the slightly pedantic missing semicolon on line 6.)

    Because the sayName function is created inside the constructor, a new function is created every time a new object is created. (So the functions are different, and == returns false)

    People get around this by attaching the function to the prototype object instead:

    function Person (name, age) {
    this.name = name;
    this.age = age;
}    

Person.prototype.sayName = function () {
    alert(this.name);
};

var person1 = new Person ("tom", 29);
var person2 = new Person ("frank", 21);
alert(person1.sayName==person2.sayName);

    This will create only one function (saving you memory) and the alert will say ‘true’.

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