Using SendKeys to Automate Repetitive Tasks

If you have ever found yourself doing a repetitive action with the mouse and keyboard, and if you have even a little programming experience, there is a good chance that you can use a text editor to whip together a sort of macro to automate the process.  

This article describes how to write short scripts that will let you "pull the strings" on an application program to make it dance to your will.  Examples will be in JavaScript code (.JS files) but the concepts here also apply to VBScript (.VBS files), in case BASIC is your language of choice.

...after double-clicking the toPng128.JS icon...Here are some example usages:

In short, this technique is handy anytime that you can accomplish some individual task with a few keystrokes but you would rather not spend the rest of the day stroking those particular keys over and over.

Important Notes:

Partial Automation
One thing I'd like to promote here is the idea of "partial automation" of a process.  As a programmer, I can always see  various ways to automate a task.  The trick is doing just the right amount of programming.  You can spend hours or days writing a program that will take care of every little detail (do the whole thing automatically), but writing the code might take longer than just doing the whole job manually!  

What I do is look for the part of the manual operation that is the most time-consuming and repetitive, and then automate just that portion.  SendKeys comes in handy in such cases.


Starter Kit
We'll be writing short programs in JavaScript.  Typical operations for this type of task include launching an application, feeding it some keystrokes, and (perhaps) popping up a message box.

I have a template script full of comments that I keep handy so that I don't need to constantly refer to the documentation.  It looks like this:
MyMacro.js

// Macro starter script -- basically a cheat-sheet of common commands
                      
                      var oShell = WScript.CreateObject("WScript.Shell");
                      
                      //oShell.AppActivate("Paint"); // Set focus to a program
                      //WScript.Sleep(500);          // Delay for 1/2 second
                      
                      //oShell.Run("notepad c:\\temp\\somefile.txt", 1, false);   // launch a program
                      //----------------------------- can add ,2 to run minimized, true=wait for exit
                      
                      //oShell.SendKeys("%F");       // Alt+F  ----- SendKeys strings to jog my memory
                      //oShell.SendKeys("^C");       // Ctrl+C
                      //oShell.SendKeys("{ENTER}");  // Send Enter key (also tilde {~} )
                      //oShell.SendKeys("{{TAB} 2"); // Send Tab key twice )
                      //oShell.SendKeys(" ");        // Send a space
                      
                      var nResult= oShell.Popup("Do you want to continue?", 0, "My Macro", 4+32 );
                      if ( nResult==6 ) { // 6=Yes, 7=No, 
                         WScript.Echo( "you said 'Yes!'" );	
                      }
                      WScript.Echo( "done!" );

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Example #1:  Insert a string at the top of a text file.

This script will open a file in Notepad, insert a copyright notice at the top, and then save the file.

1

Copy the above template to a text file on your desktop.  Rename it to SetCopyright.js

2

Right-click that .JS file and select Edit

3

Replace the contents with this:

// Example #1:
                      // Insert copyright notice at the top of a file, 
                      // and save the file with the change
                      
                      var oShell = WScript.CreateObject("WScript.Shell");
                      oShell.AppActivate("Notepad"); // Set focus to program
                      WScript.Sleep(100);            // Delay for a bit
                      
                      oShell.SendKeys("^{HOME}");    // Cursor to top of file
                      WScript.Sleep(100);            // Delay for a bit
                      oShell.SendKeys("// Copyright {(}c{)} 2010, MyCompany");  
                      WScript.Sleep(100);          
                      oShell.SendKeys("{Enter}");    // line break
                      WScript.Sleep(100);          
                      oShell.SendKeys("^s");         // Ctrl+S saves the file
                      WScript.Echo( "done!" );

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4

Save the file.

5

Double-click your SetCopyright.js icon in the desktop to run the script.The result is that whatever file is currently open in Notepad is altered, with the text...

// Copyright (c) 2010, MyCompany

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....having been inserted at the top.

Here are a couple of items to note about the above script:

The only reason to create that script would be to save you lots of repeated effort.  Let's say that you had forty files in a folder and you need to insert the copyright notice in each.   With the help of this script, the sequence becomes:

1) Open an Explorer window on the folder containing the files.
2) Open the first file in Notepad.
3) Double-click your SetCopyright.js icon.
4) Drag the next file from the Explorer window and drop it on the Notepad window.
5) Repeat steps 3-4 until done.

You will be finished before you know it!  

There are other, more sophisticated ways to do that same task, but we were able to create the macro in a few minutes that would save as much as an hour of tedious work. That's a clear win.  A more sophisticated script (for instance, one that opened each file, read it into memory and wrote it back out) would take longer to create and debug; enough longer that you might lose the cost/benefit advantage.


Example #2:  Resize a JPG image and save it as a PNG file.

Like the previous macro, this one feeds keystrokes into an application program, but this time it is MsPaint.  The "grunt work" task you've been given is to plow through a bunch of JPG files and resize them all to 128x128 and save the results as PNG files.  A tedious afternoon awaits you...

Or you can write a short script like:

ToPng128.js

// Assumes a JPG file is open in Paint.Exe
                      // Resizes it to 128x128
                      // Saves it with the same name but in PNG format and extension.
                      //
                      var oShell = WScript.CreateObject("WScript.Shell");
                      
                      oShell.AppActivate("Paint"); // Set focus to open MsPaint program
                      WScript.Sleep(500);          // Delay for 1/2 second
                      
                      //=== resize image to 128x128
                      oShell.SendKeys("%HRE");        // resize dialog box
                      oShell.SendKeys("%B{RIGHT} ");  // set radio button to pixels
                      oShell.SendKeys("%M");          // uncheck "Maintain aspect ratio"
                      oShell.SendKeys("%H128");       // horizontal
                      oShell.SendKeys("{TAB}128");    // vertical
                      oShell.SendKeys("{ENTER}");     // OK the dlg box
                      
                      oShell.SendKeys("%FA");      // File > Save As
                      WScript.Sleep(500);          // Delay for 1/2 second
                      oShell.SendKeys("%TP");      // Save as Type "PNG"
                      WScript.Sleep(500);          // Delay for 1/2 second
                      oShell.SendKeys("%S");       // save

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Here again, I aimed for "partial automation."  Your task will be to drop files onto the Paint window, then double-click the .JS file.  The macro does the rest.

The sequence of steps looks confusing but it's all straightforward.  When we need to access a menu (er..., ribbon) function, we use a ALT-shifted letter, and then send some followup letters to select the command.  For instance, to bring up the Resize and Skew dialog, the script presses ALT+H (by sending %H) then the script types RE.

With that new-fangled ribbon, how do you know what keys to press?  The program shows you!   Here's what's displayed while you are pressing the Alt key.
So ALT+HRE brings up the resizing dialog:
The script needs to:
1) Set the Pixels radio button.
2) Clear (uncheck) the Maintain aspect ratio checkbox.
3) Fill in the Horizontal and Vertical values.
4) OK the dialog.

And it does all of that in lines 11-16.

Manipulating Dialog Box Controls
In some cases, you can use {TAB} to move from control to control, but it's usually best to use the ALT-key accelerator.  For instance, to get to the Horizontal text input box, the script presses ALT+H, then types in the desired size (128).  In this dialog, sending {Enter} is the same as a click of the [OK] button.

Even a complex sequence like this is pretty easy to automate.  Just do it manually, one step at a time, taking notes as you go.  Then convert the keystrokes into SendKeys() commands.  And if you can't walk on water, you'll need to test the sequence on a "scratch file" at least a few times.  I hardly ever get everything right the first time.

After the Resize and Skew dialog box is OKed, Paint immediately resizes the image as requested.

The final steps (lines 18-22) save the file using the "Save As..." command.  To complicate the scenario, we need to jump down to the Save as type control (just send ALT+T) then select PNG format (press P) and finally Alt+S save the file and close the dialog.

As soon as one file is finished, you drag another and drop it onto Paint, double-click the script icon, and repeat.

Summary:
========

In this article, we saw how to partially automate some repetitive tasks using JavaScript, the WScript.Shell object, and its SendKeys() function.

JavaScript (and VBScript) are full-featured programming languages, so it is possible to use scripts to do a lot more than just save yourself a few keystrokes.  But quite often, you can actually finish a large task sooner by slapping together a quick script to automate just a portion of the task.


Additional Notes:

References:

SendKeys Method
http://msdn.microsoft.com/en-us/library/8c6yea83(VS.85).aspx

Windows Script Host Reference
http://msdn.microsoft.com/en-us/library/98591fh7(VS.85).aspx

JScript Language Reference (Windows Scripting - JScript)
http://msdn.microsoft.com/en-us/library/yek4tbz0(VS.85).aspx

WScript Object
http://msdn.microsoft.com/en-us/library/at5ydy31(VS.85).aspx

Run Method (Windows Script Host)
http://msdn.microsoft.com/en-us/library/d5fk67ky(VS.85).aspx

AppActivate Method
http://msdn.microsoft.com/en-us/library/wzcddbek(VS.85).aspx

WshShell Object
http://msdn.microsoft.com/en-us/library/aew9yb99(VS.85).aspx

Popup Method
http://msdn.microsoft.com/en-us/library/x83z1d9f(VS.85).aspx

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