Support multi-char deletion

Author: RasPython3

index.html

@@ -2254,8 +2254,17 @@ <h3>設定</h3>
           //console.log(document.getElementById("cursor").children[1].selectionStart, document.getElementById("cursor").children[1].selectionEnd);
           if (e.data == null || e.data == undefined) {
             if (e.inputType == "deleteContentBackward") {
+              let i = 0;
+              let count = ((range)=>range.endOffset-range.startOffset)(e.getTargetRanges()[0]);
+              while (count > 0) {
+                count -= texts[cursor_pos[0]][cursor_pos[1] - i].length;
+                i++;
+              }
               let ev = new KeyboardEvent("keydown", {key: "Backspace", isComposing: false});
-              e.target.dispatchEvent(ev);
+              while (i > 0) {
+                e.target.dispatchEvent(ev);
+                i--;
+              }
             }
             return;
           }