Translate page progressively - parallel chunks, swap text as each batch returns

public/translate.js

@@ -49,22 +49,23 @@
     var uniq=[],idx={};
     nodes.forEach(function(n){ var t=n.nodeValue.trim(); if(!(t in idx)&&memo[t]==null){ idx[t]=uniq.length; uniq.push(t);} });
     var chunks=[]; for(var i=0;i<uniq.length;i+=20)chunks.push(uniq.slice(i,i+20));
-    var p=Promise.resolve();
+    function apply(){
-    chunks.forEach(function(ch){
-      p=p.then(function(){
-        return fetch('/api/public/translate',{method:'POST',headers:{'Content-Type':'application/json'},
-          body:JSON.stringify({tl:lang,texts:ch})}).then(function(r){return r.json()}).then(function(d){
-            if(d&&Array.isArray(d.t))ch.forEach(function(t,j){ memo[t]=d.t[j]; });
-          }).catch(function(){});
-      });
-    });
-    p.then(function(){
-      saveMemo();
       nodes.forEach(function(n){
         var raw=n.nodeValue,t=raw.trim(),tr=memo[t];
         if(tr&&tr!==t){ n.nodeValue=raw.replace(t,tr); }
-        n.__rmcTr=lang;
       });
+    }
+    apply(); // whatever the memo already covers shows instantly
+    // parallel chunks, each swapped in the moment it returns — a first-ever
+    // page+language visit translates progressively instead of all-at-the-end
+    Promise.all(chunks.map(function(ch){
+      return fetch('/api/public/translate',{method:'POST',headers:{'Content-Type':'application/json'},
+        body:JSON.stringify({tl:lang,texts:ch})}).then(function(r){return r.json()}).then(function(d){
+          if(d&&Array.isArray(d.t)){ ch.forEach(function(t,j){ memo[t]=d.t[j]; }); apply(); }
+        }).catch(function(){});
+    })).then(function(){
+      saveMemo();
+      nodes.forEach(function(n){ n.__rmcTr=lang; });
       busy=false;
       if(queued){queued=false;translatePage();}
     });