Use async/await for async functions.

src/app.tsx

@@ -54,7 +54,7 @@ export class App extends React.Component<RouteComponentProps, {}> {
     this.componentDidUpdate();
   }
 
-  componentDidUpdate() {
+  async componentDidUpdate() {
     if (this.props.location.pathname !== '/view') {
       return;
     }
@@ -77,45 +77,42 @@ export class App extends React.Component<RouteComponentProps, {}> {
     if (!url && !hash) {
       this.props.history.replace({pathname: '/'});
     } else if (this.isNewData(hash, url)) {
-      const loadedData = hash
-        ? loadGedcom(hash, gedcom, images)
-        : loadFromUrl(url!, handleCors);
-      loadedData.then(
-        (data) => {
-          // Set state with data.
-          this.setState(
-            Object.assign({}, this.state, {
-              data,
-              hash,
-              selection: getSelection(data.chartData, indi, generation),
-              error: undefined,
-              loading: false,
-              url,
-              showSidePanel,
-            }),
-          );
-        },
-        (error) => {
-          // Set error state.
-          this.setState(
-            Object.assign({}, this.state, {
-              error: error.message,
-              loading: false,
-            }),
-          );
-        },
-      );
-      // Set loading state.
-      this.setState(
-        Object.assign({}, this.state, {
-          data: undefined,
-          selection: undefined,
-          hash,
-          error: undefined,
-          loading: true,
-          url,
-        }),
-      );
+      try {
+        // Set loading state.
+        this.setState(
+          Object.assign({}, this.state, {
+            data: undefined,
+            selection: undefined,
+            hash,
+            error: undefined,
+            loading: true,
+            url,
+          }),
+        );
+        const data = hash
+          ? await loadGedcom(hash, gedcom, images)
+          : await loadFromUrl(url!, handleCors);
+        // Set state with data.
+        this.setState(
+          Object.assign({}, this.state, {
+            data,
+            hash,
+            selection: getSelection(data.chartData, indi, generation),
+            error: undefined,
+            loading: false,
+            url,
+            showSidePanel,
+          }),
+        );
+      } catch (error) {
+        // Set error state.
+        this.setState(
+          Object.assign({}, this.state, {
+            error: error.message,
+            loading: false,
+          }),
+        );
+      }
     } else if (this.state.data && this.state.selection) {
       // Update selection if it has changed in the URL.
       const selection = getSelection(

src/chart.tsx

@@ -38,28 +38,29 @@ function loadAsDataUrl(blob: Blob): Promise<string> {
   });
 }
 
+async function inlineImage(image: SVGImageElement) {
+  const href = image.href.baseVal;
+  if (!href) {
+    return;
+  }
+  try {
+    const response = await fetch(href);
+    const blob = await response.blob();
+    const dataUrl = await loadAsDataUrl(blob);
+    image.href.baseVal = dataUrl;
+  } catch (e) {
+    console.warn('Failed to load image:', e);
+  }
+}
+
 /**
  * Fetches all images in the SVG and replaces them with inlined images as data
  * URLs. Images are replaced in place. The replacement is done, the returned
  * promise is resolved.
  */
-function inlineImages(svg: Element): Promise<void[]> {
+async function inlineImages(svg: Element): Promise<void> {
   const images = Array.from(svg.getElementsByTagName('image'));
-  const promises = images.map((image) => {
-    const href = image.href && image.href.baseVal;
-    if (!href) {
-      return Promise.resolve();
-    }
-    return fetch(href)
-      .then((response) => response.blob())
-      .then(loadAsDataUrl)
-      .then((dataUrl) => {
-        image.href.baseVal = dataUrl;
-      })
-      // Log and ignore errors.
-      .catch((e) => console.warn('Failed to load image:', e));
-  });
-  return Promise.all(promises);
+  await Promise.all(images.map(inlineImage));
 }
 
 /** Loads a blob into an image object. */
@@ -67,9 +68,7 @@ function loadImage(blob: Blob): Promise<HTMLImageElement> {
   const image = new Image();
   image.src = URL.createObjectURL(blob);
   return new Promise<HTMLImageElement>((resolve, reject) => {
-    image.addEventListener('load', () => {
-      resolve(image);
-    });
+    image.addEventListener('load', () => resolve(image));
   });
 }
 
@@ -215,12 +214,11 @@ export class Chart extends React.PureComponent<ChartProps, {}> {
     return new XMLSerializer().serializeToString(svg);
   }
 
-  private getSvgContentsWithInlinedImages() {
+  private async getSvgContentsWithInlinedImages() {
     const svg = document.getElementById('chart')!.cloneNode(true) as Element;
     svg.removeAttribute('transform');
-    return inlineImages(svg).then(() =>
-      new XMLSerializer().serializeToString(svg),
-    );
+    await inlineImages(svg);
+    return new XMLSerializer().serializeToString(svg);
   }
 
   /** Shows the print dialog to print the currently displayed chart. */
@@ -243,35 +241,32 @@ export class Chart extends React.PureComponent<ChartProps, {}> {
     document.body.appendChild(printWindow);
   }
 
-  downloadSvg() {
-    this.getSvgContentsWithInlinedImages().then((contents) => {
-      const blob = new Blob([contents], {type: 'image/svg+xml'});
-      saveAs(blob, 'topola.svg');
-    });
-  }
-
-  drawOnCanvas(): Promise<HTMLCanvasElement> {
-    return this.getSvgContentsWithInlinedImages()
-      .then((contents) => new Blob([contents], {type: 'image/svg+xml'}))
-      .then(loadImage)
-      .then(drawOnCanvas);
-  }
-
-  downloadPng() {
-    this.drawOnCanvas()
-      .then((canvas) => canvasToBlob(canvas, 'image/png'))
-      .then((blob) => saveAs(blob, 'topola.png'));
-  }
-
-  downloadPdf() {
-    this.drawOnCanvas().then((canvas) => {
-      const doc = new jsPDF({
-        orientation: canvas.width > canvas.height ? 'l' : 'p',
-        unit: 'pt',
-        format: [canvas.width, canvas.height],
-      });
-      doc.addImage(canvas, 'PNG', 0, 0, canvas.width, canvas.height, 'NONE');
-      doc.save('topola.pdf');
+  async downloadSvg() {
+    const contents = await this.getSvgContentsWithInlinedImages();
+    const blob = new Blob([contents], {type: 'image/svg+xml'});
+    saveAs(blob, 'topola.svg');
+  }
+
+  private async drawOnCanvas(): Promise<HTMLCanvasElement> {
+    const contents = await this.getSvgContentsWithInlinedImages();
+    const blob = new Blob([contents], {type: 'image/svg+xml'});
+    return await drawOnCanvas(await loadImage(blob));
+  }
+
+  async downloadPng() {
+    const canvas = await this.drawOnCanvas();
+    const blob = await canvasToBlob(canvas, 'image/png');
+    saveAs(blob, 'topola.png');
+  }
+
+  async downloadPdf() {
+    const canvas = await this.drawOnCanvas();
+    const doc = new jsPDF({
+      orientation: canvas.width > canvas.height ? 'l' : 'p',
+      unit: 'pt',
+      format: [canvas.width, canvas.height],
     });
+    doc.addImage(canvas, 'PNG', 0, 0, canvas.width, canvas.height, 'NONE');
+    doc.save('topola.pdf');
   }
 }

src/load_data.ts

@@ -32,37 +32,32 @@ function prepareData(
 }
 
 /** Fetches data from the given URL. Uses cors-anywhere if handleCors is true. */
-export function loadFromUrl(
+export async function loadFromUrl(
   url: string,
   handleCors: boolean,
 ): Promise<TopolaData> {
   const cachedData = sessionStorage.getItem(url);
   if (cachedData) {
-    return Promise.resolve(JSON.parse(cachedData));
+    return JSON.parse(cachedData);
   }
   const urlToFetch = handleCors
     ? 'https://cors-anywhere.herokuapp.com/' + url
     : url;
 
-  return window
-    .fetch(urlToFetch)
-    .then((response) => {
-      if (response.status !== 200) {
-        return Promise.reject(new Error(response.statusText));
-      }
-      return response.text();
-    })
-    .then((gedcom) => {
-      return prepareData(gedcom, url);
-    });
+  const response = await window.fetch(urlToFetch);
+  if (response.status !== 200) {
+    throw new Error(response.statusText);
+  }
+  const gedcom = await response.text();
+  return prepareData(gedcom, url);
 }
 
 /** Loads data from the given GEDCOM file contents. */
-function loadGedcomSync(
+export async function loadGedcom(
   hash: string,
   gedcom?: string,
   images?: Map<string, string>,
-) {
+): Promise<TopolaData> {
   const cachedData = sessionStorage.getItem(hash);
   if (cachedData) {
     return JSON.parse(cachedData);
@@ -72,16 +67,3 @@ function loadGedcomSync(
   }
   return prepareData(gedcom, hash, images);
 }
-
-/** Loads data from the given GEDCOM file contents. */
-export function loadGedcom(
-  hash: string,
-  gedcom?: string,
-  images?: Map<string, string>,
-): Promise<TopolaData> {
-  try {
-    return Promise.resolve(loadGedcomSync(hash, gedcom, images));
-  } catch (e) {
-    return Promise.reject(new Error('Failed to read GEDCOM file'));
-  }
-}

src/top_bar.tsx

@@ -39,16 +39,6 @@ function loadFileAsText(file: File): Promise<string> {
   });
 }
 
-function loadFileAsDataUrl(file: File): Promise<string> {
-  return new Promise((resolve, reject) => {
-    const reader = new FileReader();
-    reader.onload = (evt: ProgressEvent) => {
-      resolve((evt.target as FileReader).result as string);
-    };
-    reader.readAsDataURL(file);
-  });
-}
-
 function isImageFileName(fileName: string) {
   const lower = fileName.toLowerCase();
   return lower.endsWith('.jpg') || lower.endsWith('.png');
@@ -62,12 +52,14 @@ export class TopBar extends React.Component<
   inputRef?: Input;
 
   /** Handles the "Upload file" button. */
-  handleUpload(event: React.SyntheticEvent<HTMLInputElement>) {
+  async handleUpload(event: React.SyntheticEvent<HTMLInputElement>) {
     const files = (event.target as HTMLInputElement).files;
     if (!files || !files.length) {
       return;
     }
     const filesArray = Array.from(files);
+    (event.target as HTMLInputElement).value = ''; // Reset the file input.
+
     const gedcomFile =
       files.length === 1
         ? files[0]
@@ -86,20 +78,19 @@ export class TopBar extends React.Component<
     const imageMap = new Map(
       images.map((entry) => [entry.name, entry.url] as [string, string]),
     );
-    loadFileAsText(gedcomFile).then((data) => {
-      const imageFileNames = images
-        .map((image) => image.name)
-        .sort()
-        .join('|');
-      // Hash GEDCOM contents with uploaded image file names.
-      const hash = md5(md5(data) + imageFileNames);
-      this.props.history.push({
-        pathname: '/view',
-        search: queryString.stringify({file: hash}),
-        state: {data, images: imageMap},
-      });
+
+    const data = await loadFileAsText(gedcomFile);
+    const imageFileNames = images
+      .map((image) => image.name)
+      .sort()
+      .join('|');
+    // Hash GEDCOM contents with uploaded image file names.
+    const hash = md5(md5(data) + imageFileNames);
+    this.props.history.push({
+      pathname: '/view',
+      search: queryString.stringify({file: hash}),
+      state: {data, images: imageMap},
     });
-    (event.target as HTMLInputElement).value = ''; // Reset the file input.
   }
 
   /** Opens the "Load from URL" dialog. */