Initial bits for a JS API variant in which the client operates in the main thread and sqlite3 in a Worker. This is far from complete.

FossilOrigin-Name: f6d6f969791f0d2367ae5418623b4794f6df657d9d7d9002fb5aec4206dcfd4c

ext/fiddle/sqlite3-worker.js

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+/*
+  2022-05-23
+
+  The author disclaims copyright to this source code.  In place of a
+  legal notice, here is a blessing:
+
+  *   May you do good and not evil.
+  *   May you find forgiveness for yourself and forgive others.
+  *   May you share freely, never taking more than you give.
+
+  ***********************************************************************
+
+  UNDER CONSTRUCTION
+
+  This is a JS Worker file for the main sqlite3 api. It loads
+  sqlite3.js and offers access to the db via the Worker
+  message-passing interface.
+*/
+
+"use strict";
+(function(){
+    /** Posts a worker message as {type:type, data:data}. */
+    const wMsg = (type,data)=>self.postMessage({type, data});
+    self.onmessage = function(ev){
+        /*ev = ev.data;
+        switch(ev.type){
+            default: break;
+        };*/
+        console.warn("Unknown sqlite3-worker message type:",ev);
+    };
+    importScripts('sqlite3.js');
+    initSqlite3Module().then(function(){
+        wMsg('sqlite3-api','ready');
+    });
+})();