How can I use JavaScript within an Excel macro?

Question

There’s a really cool diff class hosted by Google here:

http://code.google.com/p/google-diff-match-patch/

I’ve used it before on a few web sites, but now I n

Answer 1

The simplest approach may be to embed the Javascript diff logic into a COM component directly using Javascript. This is possible via something called "Windows Script Components".

Here's a tutorial on creating WSCs.

A Windows Script Component is a COM component that is defined in script. The interface to the component is via COM, which means it is VBA friendly. The logic is implemented in any Windows Scripting Hosting -compatible language, like JavaScript or VBScript. The WSC is defined in a single XML file, which embeds the logic, the component Class ID, the methods, the registration logic, and so on.

There's also a tool available to help in creating a WSC. Basically it is a wizard-type thing that asks you questions and fills in the XML template. Myself, I just started with an example .wsc file and edited it by hand with a text editor. It's pretty self-explanatory.

A COM component defined this way in script (in a .wsc file) is callable just like any other COM component, from any environment that can dance with COM.

UPDATE: I took a few minutes and produced the WSC for GoogleDiff. Here it is.

  
    COM Wrapper on the Diff/Match/Patch logic published by Google at http://code.google.com/p/google-diff-match-patch/.
  





  




  
    
    
  
  
    
    
  

To use that thing, you have to register it. In Explorer, right click on it, and select "Register". or, from the command line: regsvr32 file:\c:\scripts\GoogleDiff.wsc

I didn't try using it from VBA, but here is some VBScript code that uses the component.

Sub TestDiff()
    dim t1 
    t1 = "The quick brown fox jumped over the lazy dog."

    dim t2 
    t2 = "The large fat elephant jumped over the cowering flea."

    WScript.echo("")

    WScript.echo("Instantiating a Diff Component ...")
    dim d
    set d = WScript.CreateObject("Cheeso.Google.DiffMatchPatch")

    WScript.echo("Doing the Diff...")
    x = d.Diff(t1, t2)

    WScript.echo("")
    WScript.echo("Result was of type: " & TypeName(x))
    ' result is all the diffs, joined by commas.  
    ' Each diff is an integer (position), and a string.  These are separated by commas.
    WScript.echo("Result : " & x)

    WScript.echo("Transform result...")
    z= Split(x, ",")
    WScript.echo("")
    redim diffs(ubound(z)/2)
    i = 0
    j = 0
    For Each item in z
      If (j = 0) then
        diffs(i) = item
        j = j+ 1      
      Else 
          diffs(i) = diffs(i) & "," & item
        i = i + 1
        j = 0
      End If
    Next

    WScript.echo("Results:")
    For Each item in diffs
      WScript.echo("  " & item)
    Next

    WScript.echo("Done.")

End Sub