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StringBuilder in JavaScript

In this article I will explain how to create an object in JavaScript which can act in a same way as StringBuilder class in .Net. This topic contains following sections

   1. Software Requirement

   2. Prerequisite Knowledge

   3. Steps to follow for creating StringBuilder in JavaScript

   4. prototype property in JavaScript

   5. Creation of StringBuilder object

   6. AppendString method of StringBuilder object

   7. ToStringValue method of StringBuilder object

   8. Use StringBuilder object for concatenation of string

   9. Output

   10. Complete Code

Software requirements

Before you start reading this tutorial you should make sure that

1. Windows any version is installed on your machine.

2. Notepad or any text editor for writing code.

Prerequisite knowledge

Before you go ahead, it is required that you should have

   1. Basic knowledge of JavaScript.

   2. Basic knowledge of HTML.

   3. Knowledge of any programming language is an added advantage.

Steps to follow for creating StringBuilder in JavaScript

Following steps will be followed

   1. Create a StringBuilder object.

   2. Add AppendString method to StringBuilder object using prototype property.

   3. Add ToStringValue method to StringBuilder object using prototype property.

   4. Call StringBuilder object and its methods to concatenate string values.

prototype property in JavaScript

prototype property allows you to add properties or methods to an object

Syntax

<object_name>.prototype.<method_or_property_name>= <value_or_function>;

Creation of StringBuilder object

var StringBuilder = function () {
   this.arr = new Array();
}

In this function we are initializing an array.

AppendString method of StringBuilder object

StringBuilder.prototype.AppendString = function (value) {
            this.arr.push(value);            
}

In this function we are entering values in an array using push() method.

ToStringValue method of StringBuilder object

StringBuilder.prototype.ToStringValue = function () {
           return this.arr.join("");
}

In this function we are concatenating values from the array using join() method and returns the concatenating string.

Use StringBuilder object for concatenation of string

var sb = new StringBuilder();
sb.AppendString("This");
sb.AppendString(" is");
sb.AppendString(" a");
sb.AppendString(" StringBuilder");
sb.AppendString(" Example");
alert(sb.ToStringValue());

Output

Click to Enlarge

Complete Code

<script type="text/javascript">
        var StringBuilder = function () {
            this.arr = new Array();
        }
        
        StringBuilder.prototype.AppendString = function (value) {
            this.arr.push(value);            
        }

        StringBuilder.prototype.ToStringValue = function () {
           return this.arr.join("");
       }
        
        var sb = new StringBuilder();
        sb.AppendString("This");
        sb.AppendString(" is");
        sb.AppendString(" a");
        sb.AppendString(" StringBuilder");
        sb.AppendString(" Example");
        alert(sb.ToStringValue());   
</script>

Posted By -	Karan Gupta

Posted On -	Thursday, August 30, 2012

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