How to add callback to method diff.structuredPatch?

Using library https://github.com/kpdecker/jsdiff and calling:

function structuredPatch(oldFileName: string, newFileName: string, oldStr: string, newStr: string, 
                         oldHeader: string, newHeader: string, options?: {context: number}): IUniDiff;

How do you pass a callback to it?

Prior to version 6.0.0, the callback option was only supported by the diffFoo family of functions, like diffChars, diffWords, etc., and not by patch-creation functions like structuredPatch. What you wanted to do was therefore simply not supported back in 2020 when you asked this question.

However, I added support for using patch-creation functions asynchronously in v6.0.0, so if you upgrade to the latest version of jsdiff you can now invoke structuredPatch in async mode like this:

structuredPatch(
  'oldfile', 'newfile',
  'foo\nbar\nbaz\n', 'foo\nbarcelona\nbaz\n',
  'header1', 'header2',
  {
    callback: (res) => {
      console.log(res);
      // Will log:
      // {
      //   oldFileName: 'oldfile', newFileName: 'newfile',
      //   oldHeader: 'header1', newHeader: 'header2',
      //   hunks: [{
      //     oldStart: 1, oldLines: 3, newStart: 1, newLines: 3,
      //     lines: [' foo', '-bar', '+barcelona', ' baz']
      //   }]
      // }
    }
);