Add file upload script and update readme (#8)

Author: surajp

README.md

@@ -115,6 +115,8 @@ $A.get("e.force:refreshView").fire();
   compound fields. I will update this section as I do so.
 - To insert `ContentVersion` make sure to set `VersionData` to base64 data.
   Refer to the example [here](./scripts/jsButton/createContactFiles.js) for details.
+- The maximum size of files I was able to upload was around 2 MB.
+  Anything larger will fail silently due to heap size limits in Apex
 
 ### Using Salesforce (and other) APIs in your script
 

scripts/jsButton/fetchAndAddFile.js

@@ -0,0 +1,35 @@
+/* Go to https://cors-anywhere.herokuapp.com/ and request access to the demo for the below `fetch` statement to work */
+/* Also add https://cors-anywhere.herokuapp.com/ to CSP trusted sites list */
+let respBlob = await fetch(
+  "https://cors-anywhere.herokuapp.com/https://www.eurofound.europa.eu/sites/default/files/ef_publication/field_ef_document/ef1663en.pdf"
+).then((resp) => resp.blob());
+
+const blobToBase64 = (blob) => {
+  return new Promise((resolve, reject) => {
+    try {
+      const reader = new FileReader();
+      reader.readAsDataURL(blob);
+      reader.onloadend = function () {
+        let base64data = reader.result;
+        debugger;
+        resolve(base64data.substring(base64data.indexOf(",") + 1));
+      };
+    } catch (e) {
+      reject(e);
+    }
+  });
+};
+
+let base64data = await blobToBase64(respBlob);
+let cv = [
+  {
+    Title: "SF.pdf",
+    VersionData: base64data,
+    PathOnClient: "Salesforce.pdf",
+    FirstPublishLocationId: recordId
+  }
+];
+let fileIds = await dml.insert(cv, "ContentVersion");
+console.log("file ids", fileIds);
+toast("File added", "success");
+$A.get("e.force:refreshView").fire();