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JavaScript String prototype Property

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  • Last Updated : 30 Jun, 2020
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The prototype property allows to add new properties and methods to the existing JavaScript object types. There are two examples to describe the JavaScript String prototype property.

Syntax:

object.prototype.name = value

Return Value: It returns a reference to the String.prototype object.

Example 1: This example adds a property salary to the all objects.




<!DOCTYPE HTML>
<html>
  
<head>
    <title>
        JavaScript String prototype Property
    </title>
</head>
  
<body style="text-align:center;">
  
    <h1>GeeksForGeeks</h1>
      
    <p id="GFG_UP"></p>
  
    <button onclick="GFG_Fun();">
        Click Here
    </button>
      
    <p id="GFG_DOWN"></p>
      
    <script>
        var up = document.getElementById('GFG_UP');
        var down = document.getElementById('GFG_DOWN');
          
        function person(name, age) {
            this.name = name;
            this.age = age;
        }
        var p1 = new person("p1", 24);
        up.innerHTML = "Click on the button to add "
                + "a new property to all objects of"
                + " a given type.< br > " 
                + JSON.stringify(p1);
  
        function GFG_Fun() {
            person.prototype.salary = 1000;
            down.innerHTML = p1.salary;
        }
    </script>
</body>
  
</html

Output:

Example 2: This example adds a method info to the all objects.




<!DOCTYPE HTML>
<html>
  
<head>
    <title>
        JavaScript String prototype Property
    </title>
</head>
  
<body style="text-align:center;">
  
    <h1>GeeksForGeeks</h1>
  
    <p id="GFG_UP"></p>
  
    <button onclick="GFG_Fun();">
        Click Here
    </button>
      
    <p id="GFG_DOWN"></p>
      
    <script>
        var up = document.getElementById('GFG_UP');
        var down = document.getElementById('GFG_DOWN');
        function person(name, age) {
            this.name = name;
            this.age = age;
        }
        var p1 = new person("p1", 22);
        up.innerHTML = "Click on the button to add"
                + " a new property to all objects "
                + "of a given type.< br > " 
                + JSON.stringify(p1);
  
        function getData(name, age) {
            return "Information of person <br>Name - '" 
                        + name + "'<br>Age - " + age;
        }
  
        function GFG_Fun() {
            person.prototype.info 
                    = getData(p1.name, p1.age);
                      
            down.innerHTML = p1.info;
        }
    </script>
</body>
  
</html

Output:


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