From 9b565a6375d72932878b16c7d6eeb5fec6d7444f Mon Sep 17 00:00:00 2001
From: Martin von Gagern <gagern@ma.tum.de>
Date: Sat, 7 Jan 2017 01:29:41 +0100
Subject: [PATCH] Include babelify step in browserify calls

This allows using ES6 syntax in our code, while maintaining backwards
compatibility for the generated file.
---
 .babelrc                     |  6 ++++++
 .eslintrc                    |  2 +-
 Makefile                     | 10 ++++++++--
 check-node-version.js        | 16 ++++++++++++++++
 contrib/auto-render/Makefile |  2 +-
 package.json                 |  3 +++
 server.js                    |  5 ++++-
 7 files changed, 39 insertions(+), 5 deletions(-)
 create mode 100644 .babelrc
 create mode 100644 check-node-version.js

diff --git a/.babelrc b/.babelrc
new file mode 100644
index 0000000..39bc17f
--- /dev/null
+++ b/.babelrc
@@ -0,0 +1,6 @@
+{
+    "presets": ["es2015"],
+    "plugins": [
+        "transform-runtime"
+    ]
+}
diff --git a/.eslintrc b/.eslintrc
index 4a29cef..fc13162 100644
--- a/.eslintrc
+++ b/.eslintrc
@@ -76,7 +76,7 @@
         "templateStrings": true
     },
     "env": {
-        // "es6": true,
+        "es6": true,
         "node": true,
         "browser": true
     },
diff --git a/Makefile b/Makefile
index 4003a35..73e858c 100644
--- a/Makefile
+++ b/Makefile
@@ -13,6 +13,12 @@ dist: build
 
 endif
 
+NODE := node # pass NODE=nodejs on Debian without package nodejs-legacy
+NODECHK := $(shell $(NODE) ./check-node-version.js)
+ifneq ($(NODECHK),OK)
+$(error "Node not found or wrong version")
+endif
+
 # Export these variables for use in contrib Makefiles
 export BUILDDIR = $(realpath build)
 export BROWSERIFY = $(realpath ./node_modules/.bin/browserify)
@@ -33,7 +39,7 @@ lint: $(NIS) katex.js server.js cli.js $(wildcard src/*.js) $(wildcard test/*.js
 	./node_modules/.bin/eslint $(filter-out %.stamp,$^)
 
 build/katex.js: katex.js $(wildcard src/*.js) $(NIS)
-	$(BROWSERIFY) $< --standalone katex > $@
+	$(BROWSERIFY) -t [ babelify ] $< --standalone katex > $@
 
 build/katex.min.js: build/katex.js
 	$(UGLIFYJS) < $< > $@
@@ -92,7 +98,7 @@ compress: build/katex.min.js build/katex.min.css
 	@printf "Total:                 %6d\n" "${TOTAL}"
 
 serve: $(NIS)
-	node server.js
+	$(NODE) server.js
 
 test: $(NIS)
 	JASMINE_CONFIG_PATH=test/jasmine.json node_modules/.bin/jasmine
diff --git a/check-node-version.js b/check-node-version.js
new file mode 100644
index 0000000..06b7d88
--- /dev/null
+++ b/check-node-version.js
@@ -0,0 +1,16 @@
+"use strict";
+
+var v = process.version;
+v = v.replace(/^v/,"");
+v = v.split(".");
+v = v.map(function(s){
+    return parseInt(s);
+});
+var a = v[0], b = v[1], c = v[2];
+if (a < 6 || (a == 6 && b < 5)) {
+    console.error("Node 6.5 or later required for development. " +
+                  "Version " + process.version + " found");
+    process.exit(1);
+} else {
+    console.log("OK");
+}
diff --git a/contrib/auto-render/Makefile b/contrib/auto-render/Makefile
index 5ae1753..e43e659 100644
--- a/contrib/auto-render/Makefile
+++ b/contrib/auto-render/Makefile
@@ -6,4 +6,4 @@ $(BUILDDIR)/contrib/auto-render.min.js: $(BUILDDIR)/auto-render.js
 	$(UGLIFYJS) < $< > $@
 
 $(BUILDDIR)/auto-render.js: auto-render.js
-	$(BROWSERIFY) $< --standalone renderMathInElement > $@
+	$(BROWSERIFY) -t [ babelify ] $< --standalone renderMathInElement > $@
diff --git a/package.json b/package.json
index e50160e..1cc1b74 100644
--- a/package.json
+++ b/package.json
@@ -15,6 +15,9 @@
   ],
   "license": "MIT",
   "devDependencies": {
+    "babel-plugin-transform-runtime": "^6.15.0",
+    "babel-preset-es2015": "^6.18.0",
+    "babelify": "^7.3.0",
     "browserify": "^13.3.0",
     "clean-css": "^3.4.23",
     "eslint": "^3.13.0",
diff --git a/server.js b/server.js
index fce958d..e565bcc 100644
--- a/server.js
+++ b/server.js
@@ -2,6 +2,7 @@
 var fs = require("fs");
 var path = require("path");
 
+var babelify = require("babelify");
 var browserify = require("browserify");
 var express = require("express");
 var glob = require("glob");
@@ -25,7 +26,9 @@ var serveBrowserified = function(file, standaloneName) {
             files = [path.join(__dirname, file)];
         }
 
-        var options = {};
+        var options = {
+            transform: [babelify]
+        };
         if (standaloneName) {
             options.standalone = standaloneName;
         }