make required Node.js version explicit in package.json

changelog.md

@@ -10,6 +10,13 @@ Since [ECharts](https://echarts.apache.org/) is the main dependency of this
 application, major version changes in ECharts will also trigger a major version
 change in this application.
 
+## Version 3.0.2 (2022-07-03)
+
+__[improvement]__
+The requirement for Node.js 8 or a later version is now explicitly stated in the
+`package.json` file. While Node.js 8 or later has been required since version
+3.0.0, this step provides clarity on the required version of Node.js.
+
 ## Version 3.0.1 (2022-06-18)
 
 __[improvement]__
@@ -38,6 +45,10 @@ background. To set a background color, use the option
 of ECharts. For example, to get the white background as in previous versions,
 add `"backgroundColor": "#ffffff"` to the chart options.
 
+Furthermore, the application will now __require at least version 8 of Node.js,__
+but the use of a later version that is still maintained (e. g. Node.js 14 LTS)
+is preferred.
+
 __[maintenance]__
 Update dependency `uuid` to 8.3.2.
 

export-server/package.json

@@ -1,6 +1,6 @@
 {
   "name": "echarts-node-export-server",
-  "version": "3.0.1",
+  "version": "3.0.2",
   "description": "ECharts Node.js export server",
   "repository": {
     "url": "https://gitlab.com/striezel/echarts-node-export-server.git",
@@ -24,5 +24,8 @@
   "dependencies": {
     "canvas": "^2.9.1",
     "uuid": "^8.3.2"
+  },
+  "engines": {
+    "node": ">=8"
   }
 }

readme.md

@@ -7,7 +7,7 @@ render [ECharts](https://echarts.apache.org/) graphs to PNG or SVG images.
 
 This application needs the following prerequisites:
 
-* Node.js (preferably the latest LTS version)
+* Node.js 8 or later (preferably the latest LTS version)
 * internet connection to download required dependencies (only once before
   first start)