sources: factor out 'Fetch source data' box into view component.

app/components/source_data_component/source_data_component.js

@@ -0,0 +1,23 @@
+class SourceDataComponent {
+  static initialize() {
+    $(document).on("change.danbooru", "#upload_source", SourceDataComponent.fetchData);
+    $(document).on("click.danbooru", ".source-data-fetch", SourceDataComponent.fetchData);
+  }
+
+  static async fetchData(e) {
+    let url = $("#upload_source,#post_source").val();
+    let ref = $("#upload_referer_url").val();
+
+    e.preventDefault();
+
+    if (/^https?:\/\//.test(url)) {
+      $(".source-data").addClass("loading");
+      await $.get("/source.js", { url: url, ref: ref });
+      $(".source-data").removeClass("loading");
+    }
+  }
+}
+
+$(document).ready(SourceDataComponent.initialize);
+
+export default SourceDataComponent;