Download page: Add version number at the beginning of the generated f…

…iles. Fix #788

download.js

@@ -454,7 +454,9 @@ function generateCode(){
 	var error = $('#download .error');
 	error.style.display = '';
 
-	buildCode(promises).then(function(res) {
+	Promise.all([buildCode(promises), getVersion()]).then(function(arr) {
+		var res = arr[0];
+		var version = arr[1];
 		var code = res.code;
 		var errors = res.errors;
 
@@ -468,7 +470,7 @@ function generateCode(){
 		for (var category in redownload) {
 			redownloadUrl += category + "=" + redownload[category].join('+') + "&";
 		}
-		redownloadUrl = "/* " + redownloadUrl.replace(/&$/,"") + " */";
+		redownloadUrl = "/* PrismJS " + version + "\n" + redownloadUrl.replace(/&$/,"") + " */";
 
 		for (var type in code) {
 			var codeElement = $('#download-' + type + ' code');
@@ -513,4 +515,10 @@ function buildCode(promises) {
 	return new Promise(f);
 }
 
+function getVersion() {
+	return getFileContents('./package.json').then(function (jsonStr) {
+		return JSON.parse(jsonStr).version;
+	});
+}
+
 })();