Use console.error() to output error messages.

Author: takaakit

behavioral-patterns/memento/gamer.mjs

@@ -55,7 +55,7 @@ export class Gamer {
                 break;
             default:
                 // Other...Exit
-                console.log(`Unexpected value.`);
+                console.error(`Unexpected value.`);
                 process.exit(1);
         }
         // ˄

creational-patterns/abstract-factory/main.mjs

@@ -20,7 +20,7 @@ readline.question(``, (data) => {
     const input = Number(data);
     readline.close();
     if (isNaN(input)) {
-        console.log(`Unexpected value.`);
+        console.error(`Unexpected value.`);
         process.exit(1);
     }
 
@@ -33,7 +33,7 @@ readline.question(``, (data) => {
             factory = new TableFactory();
             break;
         default:
-            console.log(`The value is not 1 or 2.`);
+            console.error(`The value is not 1 or 2.`);
             process.exit(1);
     }
 

creational-patterns/builder/main.mjs

@@ -39,7 +39,7 @@ readline.question(``, (data) => {
         console.log(`Output File: ${path.join(process.cwd(), fileName)}`);
     }
     else {
-        console.log(`The value is not "plain" or "html".`);
+        console.error(`The value is not "plain" or "html".`);
         process.exit(1);
     }
 });

structural-patterns/decorator/side-frame.mjs

@@ -18,7 +18,7 @@ export class SideFrame extends Frame {
         super(display);
 
         if (frameChar.length !== 1) {
-            console.log(`Only one character is allowed in a side frame.`);
+            console.error(`Only one character is allowed in a side frame.`);
             process.exit(1);
         }
         this.frameChar = frameChar;