Select suitable Node.js version at rollup-time for emscripten image

Emscripten builder image has two Node.js, installed with Emscripten and
nodesource distribution.
Recent rollup requires Node.js newer than 15, but the one installed with
Emscripten is too old (v12). Therefore, we need to prefer nodesource
distributed one at rollup-time.
Ideally, we should update Emscripten base image version and avoid
multi-version Node.js toolchains.

Author: kateinoigakukun

packages/npm-packages/ruby-wasm-emscripten/build-package.sh

@@ -14,8 +14,26 @@ ruby_root="$1"
 package_dir="$(cd "$(dirname "$0")" && pwd)"
 dist_dir="$package_dir/dist"
 
+find_compatible_node() {
+    # Find `node` executable (>= 15) in PATH
+    IFS=':' read -ra dirs <<< "$PATH"
+    for dir in "${dirs[@]}"; do
+        if [ -x "$dir/node" ]; then
+            node_version=$("$dir/node" --version)
+            if [ "${node_version:1:2}" -ge 15 ]; then
+                echo "$dir/node"
+                return
+            fi
+        fi
+    done
+    echo "node >= 15 is required to build the package" >&2
+    exit 1
+}
+
 mkdir -p "$dist_dir"
 
+nodejs="$(find_compatible_node)"
+
 cp "$ruby_root/usr/local/bin/ruby.wasm" "$dist_dir/ruby.wasm"
 cp "$ruby_root/usr/local/bin/ruby" "$dist_dir/ruby.js"
 
@@ -34,4 +52,4 @@ echo "export function loadRubyStdlib() {" >> "$ruby_stdlib_js"
     --exclude '*.gem' --exclude "libruby-static.a" >> "$ruby_stdlib_js"
 echo "}" >> "$ruby_stdlib_js"
 
-(cd "$package_dir" && npm run build)
+(cd "$package_dir" && PATH="$(dirname "$nodejs"):$PATH" npm run build)