Compress your JavaScript file by removing UN use code, or comment, whitespace, trim… to make it load faster in your web page is one of good work.
My last post which shows you how to compress css code to decrease file size
http://code2code.info/post/Efficient-stylesheet-minification-in-Net.aspx
and now, I will show all of you how to apply this technique for JavaScript.
For the demo purpose, I will create console application using both C# and VB.NET
here is c# function:
/// <summary>
/// Strips the whitespace from any .js file.
/// </summary>
private static string StripWhitespace(string content)
{
string[] lines = content.Split(new string[] { Environment.NewLine }, StringSplitOptions.RemoveEmptyEntries);
StringBuilder emptyLines = new StringBuilder();
foreach (string line in lines)
{
string s = line.Trim();
if (s.Length > 0 && !s.StartsWith("//"))
emptyLines.AppendLine(s.Trim());
}
content = emptyLines.ToString();
// remove C styles comments
content = Regex.Replace(content, "/\\*.*?\\*/", String.Empty, RegexOptions.Compiled | RegexOptions.Singleline);
//// trim left
content = Regex.Replace(content, "^\\s*", String.Empty, RegexOptions.Compiled | RegexOptions.Multiline);
//// trim right
content = Regex.Replace(content, "\\s*[\\r\\n]", "\r\n", RegexOptions.Compiled | RegexOptions.ECMAScript);
// remove whitespace beside of left curly braced
content = Regex.Replace(content, "\\s*{\\s*", "{", RegexOptions.Compiled | RegexOptions.ECMAScript);
// remove whitespace beside of coma
content = Regex.Replace(content, "\\s*,\\s*", ",", RegexOptions.Compiled | RegexOptions.ECMAScript);
// remove whitespace beside of semicolon
content = Regex.Replace(content, "\\s*;\\s*", ";", RegexOptions.Compiled | RegexOptions.ECMAScript);
// remove newline after keywords
content = Regex.Replace(content, "\\r\\n(?<=\\b(abstract|boolean|break|byte|case|catch|char|class|const|continue|default|delete|do|double|else|extends|false|
final|finally|float|for|function|goto|if|implements|import|in|instanceof|int|interface|long|native|new|null|package|
private|protected|public|return|short|static|super|switch|synchronized|this|throw|throws|transient|true|try|typeof|
var|void|while|with)\\r\\n)", " ", RegexOptions.Compiled | RegexOptions.ECMAScript);
content = Regex.Replace(content, @"[\n\r]+\s*", string.Empty); // space
return content;
}
VB.NET
Public Function StripWhitespace(ByVal content As String) As String
Dim lines() = content.Split(New String() {Environment.NewLine}, StringSplitOptions.RemoveEmptyEntries)
Dim emptyLines As New StringBuilder()
For Each line As String In lines
Dim s = line.Trim()
If s.Length > 0 AndAlso Not s.StartsWith("//") Then
emptyLines.Append(s.Trim())
End If
Next
content = emptyLines.ToString()
' remove C styles comments
content = Regex.Replace(content, "/\*.*?\*/", [String].Empty, RegexOptions.Compiled Or RegexOptions.Singleline)
content = Regex.Replace(content, "^\s*", [String].Empty, RegexOptions.Compiled Or RegexOptions.Multiline)
content = Regex.Replace(content, "\s*[\r\n]", vbCr & vbLf, RegexOptions.Compiled Or RegexOptions.ECMAScript)
' remove whitespace beside of left curly braced
content = Regex.Replace(content, "\s*{\s*", "{", RegexOptions.Compiled Or RegexOptions.ECMAScript)
' remove whitespace beside of coma
content = Regex.Replace(content, "\s*,\s*", ",", RegexOptions.Compiled Or RegexOptions.ECMAScript)
' remove whitespace beside of semicolon
content = Regex.Replace(content, "\s*;\s*", ";", RegexOptions.Compiled Or RegexOptions.ECMAScript)
' remove newline after keywords
content = Regex.Replace(content, "\\r\\n(?<=\\b(abstract|boolean|break|byte|case|catch|char|class|const|continue|default|delete|do|double|else|extends|false|final|finally|
float|for|function|goto|if|implements|import|in|instanceof|int|interface|long|native|new|null|package|private|protected|public|
return|short|static|super|switch|synchronized|this|throw|throws|transient|true|try|typeof|var|void|while|with)\\r\\n)", " ", RegexOptions.Compiled Or RegexOptions.ECMAScript)
content = Regex.Replace(content, "[\n\r]+\s*", String.Empty) ' space
Return content
End Function
Then I call this function in the Main
C#
static void Main(string[] args)
{
string content = File.ReadAllText("../../blog.js");
File.WriteAllText("../../blog-min.js", StripWhitespace(content));
Console.Write("Press any key to continue!");
Console.Read();
}
VB.NET
Sub Main()
Dim content As String = File.ReadAllText("../../blog.js")
File.WriteAllText("../../blog-min.js", StripWhitespace(content))
Console.WriteLine("Press any key to continue!`")
Console.Read()
End Sub
Done, now when you run this code, it will create a new file with compress content.
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