diff --git a/roles/nodejs/tasks/main.yml b/roles/nodejs/tasks/main.yml
index 457720c9b..38faf45e2 100644
--- a/roles/nodejs/tasks/main.yml
+++ b/roles/nodejs/tasks/main.yml
@@ -1,22 +1,51 @@
-# 2019-01-16/29: duplicate Node.js code unified thanks to @jvonau. It's used by:
-#   roles/pbx/tasks/main.yml       with roles/pbx/meta/main.yml  (for Asterisk with FreePBX, forthcoming early in 2019, see PR #1405)
+# 2019-02-03: SEE VAR nodejs_version: 10.x (FOR NOW!) IN vars/default_vars.yml
+# AND IF NEC OVERRIDE THIS IN /etc/iiab/local_vars.yml
+
+# 2019-01-16: duplicate Node.js code originally unified by @jvonau. It's used by:
 #   roles/nodered/tasks/main.yml   with roles/nodered/meta/main.yml
+#   roles/pbx/tasks/main.yml       with roles/pbx/meta/main.yml  (for Asterisk with FreePBX, forthcoming early in 2019, see PR #1405)
 #   roles/sugarizer/tasks/main.yml with roles/sugarizer/meta/main.yml
 
-# WE SHOULD TEST FOR ANY VERSIONS OF Node.js THAT MIGHT ALREADY BE INSTALLED!
-# IF THESE DO NOT MATCH {{ nodejs_version }} AS SET IN vars/defaults_vars.yml,
-# IIAB SHOULD HALT WITH AN EXPLANATION: https://github.com/iiab/iiab/issues/1445
 
-# 2019-01-16: fyi Node.js 10.x became "LTS" on 2018-10-30 but distros are
-# holding back for now: certainly Ubuntu 18.04 and even Debian 10/Buster
-# ("testing" branch) both install Node.js 8.x (instead of 10.x).  While the
-# more bleeding-edge Debian Sid ("unstable" branch) does install Node.js 10.x
-#
-# This May Change: thanks all for running "apt -a list nodejs" on Buster's
-# daily builds @ www.debian.org/devel/debian-installer/ and Disco Dingo (Ubuntu
-# 19.04) https://launchpad.net/ubuntu/+source/nodejs to keep us informed!
+# 1. TEST IF Node.js ALEADY INSTALLED & WARN AS NEC
+
+# 2019-02-03: BELOW TESTS IF 'nodejs' VERSION IS ALREADY INSTALLED:
+# IF SO & THIS DOESN'T MATCH nodejs_version AS SET IN defaults_vars.yml
+# AND/OR local_vars.yml IIAB HALTS WITH AN EXPLANATION (PR #1447)
+
+- name: Try to run 'nodejs -v' to get Node.js version
+  # 'node -v' doesn't work with older versions e.g. Ubuntu 16.04's nodejs 4.2.6
+  # Both below convert v10.15.1 to 10.x, but this is safer: (removes non-digits)
+  shell: nodejs -v | sed 's/[^0-9]*//' | sed 's/[^0-9].*/.x/'
+  #shell: nodejs -v | sed 's/^[vV]//' | sed 's/\..*/.x/'
+  register: nodejs_version_installed
+
+#- debug:
+#    var: nodejs_version_installed
+
+# When nodejs is NOT installed:
+# nodejs_version_installed.rc == 0    # Crazy with stderr below, "due to pipes"
+# nodejs_version_installed.stdout == ""
+# nodejs_version_installed.stderr == "/bin/sh: 1: nodejs: not found"
+# BOTH ABOVE (incl non-null stderr) are USED BELOW to confirm install is nec!
+
+- name: "ENFORCE PRECONDITION: Stop installing (intentionally fail) IF an installed 'nodejs' version isn't {{ nodejs_version }}"
+  fail:
+    msg: >
+      PLEASE REMOVE 'nodejs' VERSION {{ nodejs_version_installed.stdout }} AS
+      IT DOES NOT MATCH THE REQUIRED nodejs_version: {{ nodejs_version }} --
+      as set in /opt/iiab/iiab/vars/default_vars.yml and/or
+      /etc/iiab/local_vars.yml -- then re-run this IIAB installer.
+  when: nodejs_version_installed is defined and nodejs_version_installed.stdout != nodejs_version and nodejs_version_installed.stderr == ""
+
+- name: Warn if Node.js {{ nodejs_version}} already installed & might be updated
+  debug:
+    msg: "WARN: YOUR Node.js {{ nodejs_version }} MIGHT NOW BE UPDATED USING nodesource.com"
+  when: nodejs_version_installed is defined and nodejs_version_installed.stdout == nodejs_version
+
+
+# 2. INSTALL Node.js USING nodesource.com
 
-#- name: Set up Node.js {{ nodejs_version }} apt sources (debuntu distros UP TO 2017)
 - name: Set up Node.js {{ nodejs_version }} apt sources (debuntu)
   shell: curl -sL https://deb.nodesource.com/setup_{{ nodejs_version }} | bash -
   args:
@@ -26,8 +55,7 @@
   # NOT NEC TO TEST FOR is_raspbian_8 OR is_raspbian_9 AS /opt/iiab/iiab/vars/<OS>.yml
   # DEFINES THESE AS SUBSETS OF is_debian_8 OR is_debian_9 (FOR NOW!)
 
-#- name: Install Node.js {{ nodejs_version }} which includes /usr/bin/npm (debuntu distros UP TO 2017)
-- name: Install Node.js {{ nodejs_version }} which includes /usr/bin/npm (debuntu)
+- name: Install latest Node.js {{ nodejs_version }} which includes /usr/bin/npm (debuntu)
   package:
   #   name: nodejs={{ nodejs_version }}
       name: nodejs
@@ -42,6 +70,7 @@
     warn: no
   when: internet_available and is_redhat
 
+
 # 2018-07-14: BOTH STEPS ABOVE TAKE TIME, but Raspbian (apt offers npm
 # 1.4.21) & Debian 9 (apt offers no npm!) STILL NEED the above
 # nodesource.com approach to get a version of npm that works with Sugarizer:
@@ -53,7 +82,7 @@
 #
 # BUT FOR NOW: Ubuntu 18.04's apt (approach below) brings in npm 3.5.2,
 # which appears suffic "SO FAR"?  18.04's nodejs 8.10.0 is more reassuring!
-
+#
 # CRAZY IDEA: most versions of npm can upgrade themselves to the latest
 # (6.2.0 for now) using command "npm install -g npm", if that helps us in
 # future, e.g. TK's memory issue etc?  If so, be CAREFUL this puts npm
@@ -61,6 +90,11 @@
 # where it upgrades /usr/bin/npm in place:
 # https://askubuntu.com/questions/1036278/npm-is-incorrect-version-on-latest-ubuntu-18-04-installation
 
+# 2019-02-03: OLD WAY (PRIOR TO 2019) BELOW.  Since them, @m-anish helped
+# us standardize on the above nodesource.com approach i.e.
+# https://github.com/nodesource/distributions#debinstall ...across all
+# distros (so nodejs & npm always findable in /usr/bin, for Node-RED etc)
+
 # - name: Install packages nodejs {{ nodejs_version }} and npm (debuntu distros AFTER 2017, or other distros)
 #   package:
 #     name:
@@ -68,3 +102,12 @@
 #       - npm
 #     state: latest
 #   when: internet_available and not (is_debian_8 or is_debian_9 or is_ubuntu_16 or is_ubuntu_17)
+
+# 2019-01-16: fyi Node.js 10.x became "LTS" on 2018-10-30 but distros are
+# holding back for now: certainly Ubuntu 18.04 and even Debian 10/Buster
+# ("testing" branch) both install Node.js 8.x (instead of 10.x).  While the
+# more bleeding-edge Debian Sid ("unstable" branch) does install Node.js 10.x
+#
+# This May Change: thanks all for running "apt -a list nodejs" on Buster's
+# daily builds @ www.debian.org/devel/debian-installer/ and Disco Dingo (Ubuntu
+# 19.04) https://launchpad.net/ubuntu/+source/nodejs to keep us informed!