Creating Diagnostic Messages

Information can be shown in a message box. For example, the following checks to see if a variable called weight exists and, if it does not, alerts the user:

if (data_file.getVariableByName("weight") == null) 
   alert("Data file does not contain a variable called 'weight'.");

Alternatively, we can print messages in an output windows. The following prints the value of Don’t know (see the earlier example in this chapter):

log("Don't know in the age question has the value of " + dk_value);

See also

• Next worked example.
• QScript Selection Functions.
• QScript for an explanation of how to run this code.
• QScript Reference for technical information.
• JavaScript for information about the JavaScript programming language.