Added bind_children_to function to efficiently update child nodes of an HTML element based on the contents of a ListProperty.

src/core/gui/Table.ts

@@ -1,13 +1,10 @@
 import { Widget, WidgetOptions } from "./Widget";
-import { el } from "./dom";
-import {
-    ListChangeType,
-    ListProperty,
-    ListPropertyChangeEvent,
-} from "../observable/property/list/ListProperty";
+import { bind_children_to, el } from "./dom";
+import { ListProperty } from "../observable/property/list/ListProperty";
 import { Disposer } from "../observable/Disposer";
 import "./Table.css";
 import Logger = require("js-logger");
+import { Disposable } from "../observable/Disposable";
 
 const logger = Logger.get("core/gui/Table");
 
@@ -41,7 +38,6 @@ export type TableOptions<T> = WidgetOptions & {
 export class Table<T> extends Widget {
     readonly element = el.table({ class: "core_Table" });
 
-    private readonly table_disposer = this.disposable(new Disposer());
     private readonly tbody_element = el.tbody();
     private readonly footer_row_element?: HTMLTableRowElement;
     private readonly values: ListProperty<T>;
@@ -138,77 +134,54 @@ export class Table<T> extends Widget {
             this.create_footer();
         }
 
-        this.disposables(this.values.observe_list(this.update_table));
-
-        this.splice_rows(0, this.values.length.val, this.values.val);
+        this.disposables(
+            bind_children_to(this.tbody_element, this.values, this.create_row),
+            this.values.observe(this.update_footer),
+        );
 
         this.finalize_construction(Table.prototype);
     }
 
-    private update_table = (change: ListPropertyChangeEvent<T>): void => {
-        if (change.type === ListChangeType.ListChange) {
-            this.splice_rows(change.index, change.removed.length, change.inserted);
-            this.update_footer();
-        } else if (change.type === ListChangeType.ValueChange) {
-            // TODO: update rows
-        }
-    };
-
-    private splice_rows = (index: number, amount: number, inserted: T[]) => {
-        for (let i = 0; i < amount; i++) {
-            this.tbody_element.children[index].remove();
-        }
-
-        this.table_disposer.dispose_at(index, amount);
-
-        const rows = inserted.map((value, i) => this.create_row(index + i, value));
-
-        if (index >= this.tbody_element.childElementCount) {
-            this.tbody_element.append(...rows);
-        } else {
-            for (let i = 0; i < amount; i++) {
-                this.tbody_element.children[index + i].insertAdjacentElement(
-                    "beforebegin",
-                    rows[i],
-                );
-            }
-        }
-    };
-
-    private create_row = (index: number, value: T): HTMLTableRowElement => {
-        const disposer = this.table_disposer.add(new Disposer());
+    private create_row = (value: T, index: number): [HTMLTableRowElement, Disposable] => {
+        const disposer = new Disposer();
         let left = 0;
 
-        return el.tr(
-            {},
-            ...this.columns.map((column, i) => {
-                const cell = column.fixed ? el.th() : el.td();
+        return [
+            el.tr(
+                {},
+                ...this.columns.map((column, i) => {
+                    const cell = column.fixed ? el.th() : el.td();
 
-                try {
-                    const content = column.render_cell(value, disposer);
+                    try {
+                        const content = column.render_cell(value, disposer);
 
-                    cell.append(content);
+                        cell.append(content);
 
-                    if (column.input) cell.classList.add("input");
+                        if (column.input) cell.classList.add("input");
 
-                    if (column.fixed) {
-                        cell.classList.add("fixed");
-                        cell.style.left = `${left}px`;
-                        left += column.width || 0;
+                        if (column.fixed) {
+                            cell.classList.add("fixed");
+                            cell.style.left = `${left}px`;
+                            left += column.width || 0;
+                        }
+
+                        cell.style.width = `${column.width}px`;
+
+                        if (column.text_align) cell.style.textAlign = column.text_align;
+
+                        if (column.tooltip) cell.title = column.tooltip(value);
+                    } catch (e) {
+                        logger.warn(
+                            `Error while rendering cell for index ${index}, column ${i}.`,
+                            e,
+                        );
                     }
 
-                    cell.style.width = `${column.width}px`;
-
-                    if (column.text_align) cell.style.textAlign = column.text_align;
-
-                    if (column.tooltip) cell.title = column.tooltip(value);
-                } catch (e) {
-                    logger.warn(`Error while rendering cell for index ${index}, column ${i}.`, e);
-                }
-
-                return cell;
-            }),
-        );
+                    return cell;
+                }),
+            ),
+            disposer,
+        ];
     };
 
     private create_footer(): void {
@@ -240,7 +213,7 @@ export class Table<T> extends Widget {
         this.footer_row_element!.append(...footer_cells);
     }
 
-    private update_footer(): void {
+    private update_footer = (): void => {
         if (!this.footer_row_element) return;
 
         const col_count = this.columns.length;
@@ -254,5 +227,5 @@ export class Table<T> extends Widget {
                 cell.title = column.footer.tooltip ? column.footer.tooltip() : "";
             }
         }
-    }
+    };
 }

src/core/gui/dom.ts

@@ -2,6 +2,12 @@ import { Disposable } from "../observable/Disposable";
 import { Observable } from "../observable/Observable";
 import { is_property } from "../observable/property/Property";
 import { SectionId } from "../model";
+import {
+    ListChangeType,
+    ListProperty,
+    ListPropertyChangeEvent,
+} from "../observable/property/list/ListProperty";
+import { Disposer } from "../observable/Disposer";
 
 type ElementAttributes = {
     class?: string;
@@ -188,3 +194,56 @@ export function disposable_listener(
         },
     };
 }
+
+export function bind_children_to<T>(
+    element: HTMLElement,
+    list: ListProperty<T>,
+    create_child: (value: T, index: number) => HTMLElement | [HTMLElement, Disposable],
+): Disposable {
+    const children_disposer = new Disposer();
+
+    const observer = list.observe_list((change: ListPropertyChangeEvent<T>) => {
+        if (change.type === ListChangeType.ListChange) {
+            splice_children(change.index, change.removed.length, change.inserted);
+        } else if (change.type === ListChangeType.ValueChange) {
+            // TODO: update children
+        }
+    });
+
+    function splice_children(index: number, removed_count: number, inserted: T[]): void {
+        for (let i = 0; i < removed_count; i++) {
+            element.children[index].remove();
+        }
+
+        children_disposer.dispose_at(index, removed_count);
+
+        const children = inserted.map((value, i) => {
+            const child = create_child(value, index + i);
+
+            if (Array.isArray(child)) {
+                children_disposer.insert(index + i, child[1]);
+                return child[0];
+            } else {
+                return child;
+            }
+        });
+
+        if (index >= element.childElementCount) {
+            element.append(...children);
+        } else {
+            for (let i = 0; i < removed_count; i++) {
+                element.children[index + i].insertAdjacentElement("beforebegin", children[i]);
+            }
+        }
+    }
+
+    splice_children(0, 0, list.val);
+
+    return {
+        dispose(): void {
+            observer.dispose();
+            children_disposer.dispose();
+            element.innerHTML = "";
+        },
+    };
+}

src/hunt_optimizer/gui/WantedItemsView.ts

@@ -1,24 +1,20 @@
-import { el, Icon } from "../../core/gui/dom";
+import { bind_children_to, el, Icon } from "../../core/gui/dom";
 import "./WantedItemsView.css";
 import { Button } from "../../core/gui/Button";
 import { Disposer } from "../../core/observable/Disposer";
 import { Widget } from "../../core/gui/Widget";
-import {
-    ListChangeType,
-    ListPropertyChangeEvent,
-} from "../../core/observable/property/list/ListProperty";
 import { WantedItemModel } from "../model";
 import { NumberInput } from "../../core/gui/NumberInput";
 import { hunt_optimizer_stores } from "../stores/HuntOptimizerStore";
 import { ComboBox } from "../../core/gui/ComboBox";
 import { list_property } from "../../core/observable";
 import { ItemType } from "../../core/model/items";
+import { Disposable } from "../../core/observable/Disposable";
 
 export class WantedItemsView extends Widget {
     readonly element = el.div({ class: "hunt_optimizer_WantedItemsView" });
 
     private readonly tbody_element = el.tbody();
-    private readonly table_disposer = this.disposable(new Disposer());
     private readonly store_disposer = this.disposable(new Disposer());
 
     constructor() {
@@ -56,7 +52,11 @@ export class WantedItemsView extends Widget {
                     this.store_disposer.dispose_all();
 
                     this.store_disposer.add_all(
-                        hunt_optimizer_store.wanted_items.observe_list(this.update_table),
+                        bind_children_to(
+                            this.tbody_element,
+                            hunt_optimizer_store.wanted_items,
+                            this.create_row,
+                        ),
 
                         combo_box.selected.observe(({ value: item_type }) => {
                             if (item_type) {
@@ -78,31 +78,8 @@ export class WantedItemsView extends Widget {
         this.finalize_construction(WantedItemsView.prototype);
     }
 
-    private update_table = (change: ListPropertyChangeEvent<WantedItemModel>): void => {
-        if (change.type === ListChangeType.ListChange) {
-            for (let i = 0; i < change.removed.length; i++) {
-                this.tbody_element.children[change.index].remove();
-            }
-
-            this.table_disposer.dispose_at(change.index, change.removed.length);
-
-            const rows = change.inserted.map(this.create_row);
-
-            if (change.index >= this.tbody_element.childElementCount) {
-                this.tbody_element.append(...rows);
-            } else {
-                for (let i = 0; i < change.inserted.length; i++) {
-                    this.tbody_element.children[change.index + i].insertAdjacentElement(
-                        "beforebegin",
-                        rows[i],
-                    );
-                }
-            }
-        }
-    };
-
-    private create_row = (wanted_item: WantedItemModel): HTMLTableRowElement => {
-        const row_disposer = this.table_disposer.add(new Disposer());
+    private create_row = (wanted_item: WantedItemModel): [HTMLTableRowElement, Disposable] => {
+        const row_disposer = new Disposer();
 
         const amount_input = row_disposer.add(
             new NumberInput(wanted_item.amount.val, { min: 0, step: 1 }),
@@ -121,11 +98,14 @@ export class WantedItemsView extends Widget {
             ),
         );
 
-        return el.tr(
-            {},
-            el.td({}, amount_input.element),
-            el.td({ text: wanted_item.item_type.name }),
-            el.td({}, remove_button.element),
-        );
+        return [
+            el.tr(
+                {},
+                el.td({}, amount_input.element),
+                el.td({ text: wanted_item.item_type.name }),
+                el.td({}, remove_button.element),
+            ),
+            row_disposer,
+        ];
     };
 }