From a014f3dc02c041b5c5a7c418f2cbc748b0a6bcc2 Mon Sep 17 00:00:00 2001
From: Marshall Lochbaum <mwlochbaum@gmail.com>
Date: Sat, 10 Apr 2021 18:23:07 -0400
Subject: =?UTF-8?q?=E2=80=A2JS=20for=20Javascript=20evaluation?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 docs/bqn.js  | 16 +++++++++++++++-
 docs/repl.js |  4 +++-
 2 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/docs/bqn.js b/docs/bqn.js
index e104f4f8..d7e117ea 100755
--- a/docs/bqn.js
+++ b/docs/bqn.js
@@ -311,8 +311,22 @@ let fmtErr = (s,e) => {
 }
 
 let unixtime = (x,w) => Date.now()/1000;
+let dojs = (x,w) => {
+  if (!(x.sh && x.sh.length==1 && x.every(c=>typeof c==="string")))
+    throw Error("•JS 𝕩: 𝕩 must be a string");
+  if (has(w)) throw Error("•JS: 𝕨 not allowed");
+  let r = Function("'use strict'; return ("+x.join("")+")")();
+  let toBQN = x => {
+    if (isnum(x)) return x;
+    if (typeof x==='string') { if (Array.from(x).length!==1) throw Error("•JS: JS strings are one character; use Array.from for BQN strings"); return x; }
+    if (x instanceof Array) return arr(x.map(toBQN),x.sh||[x.length],toBQN(x.fill));
+    if (isfunc(x)) { let f=(a,b)=>toBQN(x(a,b)); f.m=x.m; return f; }
+    throw Error("•JS: Unrecognized JS result");
+  }
+  return toBQN(r);
+}
 let sysvals = {
-  bqn, type, glyph, decompose, fmt:fmt1, listsys:0,
+  bqn, js:dojs, type, glyph, decompose, fmt:fmt1, listsys:0,
   unixtime
 };
 
diff --git a/docs/repl.js b/docs/repl.js
index 4bdb653f..ec79324f 100644
--- a/docs/repl.js
+++ b/docs/repl.js
@@ -33,6 +33,7 @@ let repl = ()=>{
       doc.rslt.classList.add('err');
       doc.rslt.textContent=fmtErr(src,e);
     }
+    sysvals.js=dojs; // In case it was disabled by fragment loading
   }, 0);
 }
 if (doc.run) doc.run.onclick = repl;
@@ -158,7 +159,8 @@ if (location.hash) {
     b=new Uint8Array([...b].map(c=>c.charCodeAt(0)));
     setcount(doc.code.value = (new TextDecoder()).decode(b));
     if (ee && doc.doexplain) doc.doexplain.onclick();
-    if (run) repl();
+    nojs = () => { throw Error("Possible script injection; press Run to confirm"); }
+    if (run) { sysvals.js=nojs; repl(); }
     doc.code.focus();
   }
 }
-- 
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