build_demo_web.sh: add --fast flag to skip optimization step

sh/build_demo_web.sh

@@ -3,9 +3,33 @@ set -eu
 script_path=$( cd "$(dirname "${BASH_SOURCE[0]}")" ; pwd -P )
 cd "$script_path/.."
 
-# Usage: build_demo_web.sh [--open]
-
 CRATE_NAME="egui_demo_app"
+FEATURES="http,persistence,screen_reader"
+
+OPEN=false
+FAST=false
+
+while test $# -gt 0; do
+  case "$1" in
+    -h|--help)
+      echo "build_demo_web.sh [--fast] [--open]"
+      echo "  --fast: skip optimization step"
+      echo "  --open: open the result in a browser"
+      exit 0
+      ;;
+    --fast)
+      shift
+      FAST=true
+      ;;
+    --open)
+      shift
+      OPEN=true
+      ;;
+    *)
+      break
+      ;;
+  esac
+done
 
 # This is required to enable the web_sys clipboard API which egui_web uses
 # https://rustwasm.github.io/wasm-bindgen/api/web_sys/struct.Clipboard.html
@@ -17,7 +41,6 @@ rm -f docs/${CRATE_NAME}_bg.wasm
 
 echo "Building rust…"
 BUILD=release
-FEATURES="http,persistence,screen_reader"
 
 cargo build \
   -p ${CRATE_NAME} \
@@ -34,12 +57,15 @@ wasm-bindgen "target/wasm32-unknown-unknown/$BUILD/$TARGET_NAME" \
 # to get wasm-strip:  apt/brew/dnf install wabt
 # wasm-strip docs/${CRATE_NAME}_bg.wasm
 
+if [ "${FAST}" = false ]; then
   echo "Optimizing wasm…"
   # to get wasm-opt:  apt/brew/dnf install binaryen
   wasm-opt docs/${CRATE_NAME}_bg.wasm -O2 --fast-math -o docs/${CRATE_NAME}_bg.wasm # add -g to get debug symbols
+fi
+
 echo "Finished docs/${CRATE_NAME}_bg.wasm"
 
-if [[ "${1:-}" == "--open" ]]; then
+if [ "${OPEN}" = true ]; then
   if [[ "$OSTYPE" == "linux-gnu"* ]]; then
     # Linux, ex: Fedora
     xdg-open http://localhost:8888/index.html