From ab1881cd9f2746ad8e75ba573be34041f95ab5a6 Mon Sep 17 00:00:00 2001
From: daurnimator <quae@daurnimator.com>
Date: Thu, 28 Dec 2017 19:49:36 +1100
Subject: src/ldblib.js: Use window.prompt to get input in browser

Doesn't work in web workers
---
 README.md     |  1 +
 src/ldblib.js | 22 ++++++++++++++++------
 2 files changed, 17 insertions(+), 6 deletions(-)

diff --git a/README.md b/README.md
index 0f197ce..1b58b91 100644
--- a/README.md
+++ b/README.md
@@ -64,6 +64,7 @@ In the browser `require` and `package.loadlib` try to find a file by making sync
     - `os.rename`
     - `os.tmpname`
     - `os.execute`
+- `debug.debug()` doesn't work from web workers due to lack of a method to get synchronous user input
 - [Weak tables](http://www.lua.org/manual/5.3/manual.html#2.5.2)
 
 
diff --git a/src/ldblib.js b/src/ldblib.js
index a189976..940c525 100644
--- a/src/ldblib.js
+++ b/src/ldblib.js
@@ -395,16 +395,28 @@ const dblib = {
     "upvaluejoin":  db_upvaluejoin
 };
 
+let getinput;
 if (typeof process !== "undefined") { // Only with Node
     const readlineSync = require('readline-sync');
     readlineSync.setDefaultOptions({
         prompt: 'lua_debug> '
     });
-
-    // TODO: if in browser, use a designated input in the DOM ?
-    const db_debug = function(L) {
+    getinput = function() {
+        return readlineSync.prompt();
+    };
+} else if (typeof window !== "undefined") {
+    /* if in browser use window.prompt. Doesn't work from web workers.
+       See https://developer.mozilla.org/en-US/docs/Web/API/Window/prompt
+    */
+    getinput = function() {
+        let input = prompt("lua_debug>", "");
+        return (input !== null) ? input : "";
+    };
+}
+if (getinput) {
+    dblib.debug = function(L) {
         for (;;) {
-            let input = readlineSync.prompt();
+            let input = getinput();
 
             if (input === "cont")
                 return 0;
@@ -420,8 +432,6 @@ if (typeof process !== "undefined") { // Only with Node
             lua.lua_settop(L, 0);  /* remove eventual returns */
         }
     };
-
-    dblib.debug = db_debug;
 }
 
 const luaopen_debug = function(L) {
-- 
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