我找到了以下gitDSL函数来访问单个文件中的信息

//This should make it really easy to do work when specific keypaths have changed inside a JSON file.
JSONDiffForFile(filename: string) => Promise

// Provides a JSON patch (rfc6902) between the two versions of a JSON file, returns null if you don't have any changes for the file in the diff.

// Note that if you are looking to just see changes like: before, after, added or removed - you should use `JSONDiffForFile` instead, as this can be a bit unwieldy for a Dangerfile.
JSONPatchForFile(filename: string) => Promise

// Offers the diff for a specific file
diffForFile(filename: string) => Promise

// Offers the overall lines of code added/removed in the diff
linesOfCode() => Promise

// Offers the structured diff for a specific file
structuredDiffForFile(filename: string) => Promise

（有关这些功能的文档：https://danger.systems/js/reference.html#GitDSL)
使用danger.git.structuredDiffForFile，我可以计算出要排除的行，因此

const file = 'yarn.lock';
  const diff1 = await danger.git.structuredDiffForFile(file);
  const excludedLines = diff1.chunks[0].changes.length

这样做效果很好：

import { markdown, message, danger, warn } from "danger";
import minimatch from "minimatch";

const pr = danger.github.pr;
const modifiedFiles = danger.git.modified_files;

(async function () {
    // Encourage smaller PRs
    await checkPRSize();
    
})();

async function checkPRSize() {
  const MAX_ADDITIONS_COUNT = 500;

  const ignoredLineCount = await getIgnoredLineCount();

  if (pr.additions - ignoredLineCount > MAX_ADDITIONS_COUNT) {
    warn("Its too big!");
  }
}

// Get the number of additions in files that we want to ignore
// so that we can subtract them from the total additions
// Use a glob to match multiple files in different location
async function getIgnoredLineCount(): Promise<number> {
  let ignoredLineCount = 0;
  const IGNORE_FILE_GLOB = "**/*+(.schema.json|package.lock)";
  const ignoredFiles = modifiedFiles.filter((file) =>
    minimatch(file, IGNORE_FILE_GLOB)
  );

  await Promise.all(
    ignoredFiles.map(async (file) => {
      const diff = await danger.git.structuredDiffForFile(file);
      diff.chunks.map((chunk) => {
        // Here we filter to only get the additions
        const additions = chunk.changes.filter(({ type }) => type === "add");
        ignoredLineCount = ignoredLineCount + additions.length;
      });
    })
  );

  return ignoredLineCount;
}

我们使用glob模式来指定要排除的文件：

const linesCount = await danger.git.linesOfCode('**/*');
  // exclude fixtures and auto generated files
  const excludeLinesCount = await danger.git.linesOfCode(
    '{**/schemaTypes.ts,fixtures/**,package*.json,**/*.spec.ts,**/*.md}',
  );
  const totalLinesCount = linesCount - excludeLinesCount;