Checking to See if a Data File Has Been Imported

The following script checks to see if a data file has already been imported into the project and, if it has, it stops the script from running and tells the user “Run this script from a fresh copy of Q, with no project open.”:

assert(project.dataFiles.length == 0, "Run this script from a fresh copy of Q, with no project open.");

• project.dataFiles returns the data files in the project as an array (which is basically a list).
• project.dataFiles.length works out the length of the array of data files (i.e., counts the number of data files in the project).
• project.dataFiles.length == 0 returns a true of the number of data files is 0 and a false otherwise.
• assert(condition,message) checks that condition is true. If not your script will be aborted.

See also

• Next worked example.
• QScript for an explanation of how to run this code.
• QScript Examples Library for other examples.
• QScript Reference for technical information.
• JavaScript for information about the JavaScript programming language.
• Table JavaScript and Plot JavaScript for tools for using JavaScript to modify the appearance of tables and charts.
• JavaScript Variables for detail on how to create new variables in the Variables and Questions tab using JavaScript.