add node command

cmd/node.go

@@ -0,0 +1,38 @@
+package cmd
+
+import (
+	"errors"
+	"fmt"
+	"os/exec"
+	"strings"
+)
+
+var NodeNotFound = errors.New("nodejs not found")
+
+func Node(args ...string) (output string, err error) {
+
+	if _, err := Which("node"); err != nil {
+		if errors.Is(err, ErrNotFound) {
+			return "", NodeNotFound
+		} else {
+			return "", err
+		}
+	}
+
+	command := exec.Command("node", args...)
+
+	outputBytes, err := command.Output()
+	if err != nil {
+		var exitErr *exec.ExitError
+		if errors.As(err, &exitErr) {
+			if exitErr.ExitCode() == 1 {
+				return "", ErrNotFound
+			} else {
+				return "", fmt.Errorf("command error: %w", err)
+			}
+		}
+	}
+
+	return strings.Trim(string(outputBytes), "\n"), nil
+
+}

cmd/which.go

@@ -9,7 +9,7 @@ import (
 
 var ErrNotFound = errors.New("which: command not found")
 
-func Which(cmd string) (string, error) {
+func Which(cmd string) (dir string, err error) {
 
 	command := exec.Command("which", cmd)