使用JSOM检查文件或文件夹是否存在

How to Check with SharePoint JSOM if File or Folder Exists

Here’s a code snippet showing how to use SharePoint’s JavaScript Object Model (JSOM) to determine whether a file or folder exists:

var ctx = SP.ClientContext.get_current();

// Could also call getFileByServerRelativeUrl() here. Doesn't matter.
// The way this works is identical for files and folders.
var folder = ctx.get_web().getFolderByServerRelativeUrl("/path/to/folder");

ctx.load(folder, "Exists", "Name");

ctx.executeQueryAsync(
   function() {
      if (folder.get_exists()) {
         // Folder exists and isn't hidden from us. Print its name.
         console.log(folder.get_name());
      }
      else {
         console.log("Folder exists but is hidden (security-trimmed) for us.");
      }
   },
   function(s, args) {
      if (args.get_errorTypeName() === "System.IO.FileNotFoundException") {
         // Folder doesn't exist at all.
         console.log("Folder does not exist.");
      }
      else {
         // An unexpected error occurred.
         console.log("Error: " + args.get_message());
      }
   }
);

The behavior of the client-side object model is slightly different depending whether the file or folder truly doesn’t exist or is just being hidden from us due to security-trimming.

The code snippet above takes this distinction into account and shows you how to check for both conditions.

You can also issue a CAML query against a document library (if that’s where your file/folder lives) to see if an item representing your file/folder exists, but the above snippet is intended to demonstrate the procedure for actual SP.File and SP.Folder objects.

原文地址：https://yieldreturnpost.wordpress.com/2015/08/25/how-to-check-with-sharepoint-jsom-if-file-or-folder-exists/