Jul
03
JavaScript - String Builder Plugin
In continuing with my theme of porting useful C# functionality to JavaScript I have desided to add C#’s StringBuilder class to JavaScript in the form of String.builder.
When simply concatenating strings the string builder class may not be of much use since a simple += will suffice but when you need to go deeper and manipulate that concatenated string then the string builder really shines.
The string builder class has 6 methods to work with.
| Method Name | Method Use |
|---|---|
| append(string) | adds string to the end of the string |
| clear() | clears the internal buffer |
| insert(index, string) | inserts string into the given buffer index overriding the existing value |
| remove(string) remove(index, length) |
this method is overloaded 1 of 2: removes all occurances of string 2 of 2: removes stating at index and removes length number of indexes |
| replace(findThis, replaceWith) | replaces all occurances of findThis with replaceWith |
| toString() | returns the concatentated string |
Below is the source code for this class and a simple example of it’s use.
JavaScript
if(!String.builder)
{
String.builder = function()
{
var buffer = [];
this.append = function(str)
{
buffer.push(str);
}
this.clear = function()
{
buffer = null;
buffer = [];
}
this.insert = function(index, str)
{
if(buffer[index]){buffer[index] = str;}
else{return false;}
}
this.replace = function(find, replace)
{
for(var i=0;i<buffer.length;i++)
{
var exp = new RegExp(find,'gm');
buffer[i] = buffer[i].replace(exp,replace);
}
}
this.remove = function()
{
if(typeof arguments[0] == "string")
{
for(var i=0;i<buffer.length;i++)
{
if(arguments[0] == buffer[i]){buffer.splice(i, 1);}
}
}
else
{
var index = arguments[0];
var length = (arguments.length > 1) ? arguments[1] : 1;
buffer.splice(index,length);
}
}
this.toString = function()
{
var str = "";
for(var i=0;i<buffer.length;i++)
{
str += buffer[i];
}
return str;
}
}
}
HTML
<html>
<head>
<title></title>
<script src="StringBuilder.js"></script>
<script>
var sb = new String.builder();
sb.append("hi");
sb.append("there");
sb.append(",");
sb.append(" ");
sb.append("how");
sb.append("are");
sb.append("you");
sb.append("?");
//sb.clear();
//sb.insert(1," there");
//sb.replace("how","how ");
//sb.remove("how");
//sb.remove(4,3);
alert(sb.toString());
</script>
</head>
<body>
</body>
</html>
RSS ?
3 comments on this post
in the .toString method why not just:
return buffer.join(”");
executes much quicker
Are you aware that stringbuilder already exists in the ASP.NET AJAX client side libraries?
http://ajax.asp.net/docs/ClientReference/Sys/StringBuilderClass/default.aspx
As surprised as you might be, as a .Net developer I have just about zero experience with the ASP.Net AJAX framework. I generally use Mootools which is missing the string builder class as well as String.Format which I posted earlier. I also use the AjaxManager from Telerik.