fix: tidying up logic and adding descriptive comments

src/SASjs.ts

@@ -79,7 +79,8 @@ export default class SASjs {
   }
 
   /**
-   * Executes the sas code against SAS9 server
+   * Executes code against a SAS 9 server.  Requires a runner to be present in
+   * the users home directory in metadata.
    * @param linesOfCode - lines of sas code from the file to run.
    * @param username - a string representing the username.
    * @param password - a string representing the password.
@@ -99,7 +100,7 @@ export default class SASjs {
   }
 
   /**
-   * Executes the sas code against SASViya server
+   * Executes sas code in a SAS Viya compute session.
    * @param fileName - name of the file to run. It will be converted to path to the file being submitted for execution.
    * @param linesOfCode - lines of sas code from the file to run.
    * @param contextName - context name on which code will be run on the server.
@@ -643,7 +644,8 @@ export default class SASjs {
   }
 
   /**
-   * Makes a request to the SAS Service specified in `SASjob`. The response
+   * Makes a request to program specified in `SASjob` (could be a Viya Job, a
+   * SAS 9 Stored Process, or a SASjs Server Stored Program). The response
    * object will always contain table names in lowercase, and column names in
    * uppercase. Values are returned formatted by default, unformatted
    * values can be configured as an option in the `%webout` macro.
@@ -652,7 +654,8 @@ export default class SASjs {
    *  the SAS `_program` parameter to run a Job Definition or SAS 9 Stored
    *  Process). Is prepended at runtime with the value of `appLoc`.
    * @param data - a JSON object containing one or more tables to be sent to
-   * SAS. Can be `null` if no inputs required.
+   * SAS.  For an example of the table structure, see the project README. This
+   * value can be `null` if no inputs are required.
    * @param config - provide any changes to the config here, for instance to
    * enable/disable `debug`. Any change provided will override the global config,
    * for that particular function call.
@@ -682,18 +685,40 @@ export default class SASjs {
 
     const validationResult = this.validateInput(data)
 
+    // status is true if the data passes validation checks above
     if (validationResult.status) {
       if (config.serverType === ServerType.Sasjs) {
-        return await this.sasJsJobExecutor!.execute(
-          sasJob,
-          data,
-          config,
-          loginRequiredCallback,
-          authConfig,
-          extraResponseAttributes
-        )
+        /**
+         * When sending the JSON data object to SAS, it is first converted to 
+         * a set of specially formatted CSVs.  These are passed as multi-part
+         * form data (converted to input files in the backend SAS session by the
+         * API). When running outside of a browser, the FormData object is not 
+         * available. So in this case, a slightly different executor is invoked, 
+         * which is similar to the sas9JobExecutor.
+         */
+        if (typeof FormData === 'undefined') {
+          // cli invocation
+          return await this.sasJsJobExecutor!.execute(
+            sasJob,
+            data,
+            config,
+            loginRequiredCallback,
+            authConfig,
+            extraResponseAttributes
+          )
+        } else {
+          // web invocation
+          return await this.webJobExecutor!.execute(
+            sasJob,
+            data,
+            config,
+            loginRequiredCallback,
+            authConfig,
+            extraResponseAttributes
+          )
+        }
       } else if (
-        config.serverType !== ServerType.Sas9 &&
+        config.serverType === ServerType.SasViya &&
         config.useComputeApi !== undefined &&
         config.useComputeApi !== null
       ) {

src/job-execution/WebJobExecutor.ts

@@ -108,6 +108,8 @@ export class WebJobExecutor extends BaseJobExecutor {
       ...this.getRequestParams(config)
     }
 
+    // FormData is only valid in browser
+    // FormData is a part of JS web API (not included in native NodeJS).
     let formData = new FormData()
 
     if (data) {