/#{1,6}.+(?=\n)/g

• #{1,6}...与字符#至少匹配一次，或者作为最多6个相等字符的序列。
• .+匹配任何字符（行终止符除外）至少一次，并尽可能多地匹配（贪婪）
• 这样做，直到 positive lookahead(?=\n)匹配…
• 也就是... \n...一个换行符。
• 使用g全局修饰符，它匹配所有内容。
  编辑

已经提到

• “匹配任何字符（行终止符除外）"*

因此，像... /#{1,6}.+/g...这样的正则表达式应该已经完成OP用例的工作（不需要积极的前瞻），OP用例是...

• “markdown中的标题以#开头（可以是1-6），在我的情况下总是以新行结束。"*
  我想得到的结果是：["# Clean-er ReactJS Code - Conditional Rendering", "## TL;DR", "## Introduction"] .

const testString = `\n# Clean-er ReactJS Code - Conditional Rendering\n\n## TL;DR\n\nMove render conditions into appropriately named variables. Abstract the condition logic into a function. This makes the render function code a lot easier to understand, refactor, reuse, test, and think about.\n\n## Introduction\n\nConditional rendering is when a logical operator determines what will be rendered. The following code is from the examples in the official ReactJS documentation. It is one of the simplest examples of conditional rendering that I can think of.\n\n`;

// see...[https://regex101.com/r/n6XQub/2]
const regXHeader = /#{1,6}.+/g

console.log(
  testString.match(regXHeader)
);

.as-console-wrapper { min-height: 100%!important; top: 0; }

奖金

将上面的正则表达式重构为例如/(?<flag>#{1,6})\s+(?<content>.+)/g，通过利用 named capturing groups 以及matchAll和map ping任务，可以实现如下提供的示例代码计算的结果...

const testString = `\n# Clean-er ReactJS Code - Conditional Rendering\n\n## TL;DR\n\nMove render conditions into appropriately named variables. Abstract the condition logic into a function. This makes the render function code a lot easier to understand, refactor, reuse, test, and think about.\n\n## Introduction\n\nConditional rendering is when a logical operator determines what will be rendered. The following code is from the examples in the official ReactJS documentation. It is one of the simplest examples of conditional rendering that I can think of.\n\n`;

// see...[https://regex101.com/r/n6XQub/4]
const regXHeader = /(?<flag>#{1,6})\s+(?<content>.+)/g

console.log(
  Array
    .from(
      testString.matchAll(regXHeader)
    )
    .map(({ groups: { flag, content } }) => ({
      heading: `h${ flag.length }`,
      content,
    }))
);

.as-console-wrapper { min-height: 100%!important; top: 0; }

问题是，您正在使用正则表达式的文字，不应该对反斜杠进行双转义，因此您可以将其写成(?<!#)#{1,6} (.*?)(\r(?:\n)?|\n)
您可以缩短模式，捕获您想要的内容，并匹配尾随的换行符，而不是使用lookbehindAssert。

(#{1,6} .*)\r?\n

正在检索所有捕获组1值：

const testString = "\n# Clean-er ReactJS Code - Conditional Rendering\n\n## TL;DR\n\nMove render conditions into appropriately named variables. Abstract the condition logic into a function. This makes the render function code a lot easier to understand, refactor, reuse, test, and think about.\n\n## Introduction\n\nConditional rendering is when a logical operator determines what will be rendered. The following code is from the examples in the official ReactJS documentation. It is one of the simplest examples of conditional rendering that I can think of.\n\n"
const HEADING_R = /(#{1,6} .*)\r?\n/g;
const headings = Array.from(testString.matchAll(HEADING_R), m => m[1]);
console.log('headings: ', headings);

角箱：在许多编程语言中，注解掉的代码行以#开头，与标题相同-例如Bash，Ruby，Python。它看起来像这样：

# run command
npm install

表示此的示例markdown字符串为：

const md = "\n# Bash\n\n```\n# nuke OS\nfork()\n```\n"

迄今为止，没有任何答案可以解决这个问题。一个可能的解决方案是事先删除所有代码块：

const md = "\n# Clean-er ReactJS Code - Conditional Rendering\n\n```bash\n# initialize project via CLI\nnpm create-react-app conditional-rendering\n```\n\n\n## TL;DR\n\nMove render conditions into appropriately named variables. Abstract the condition logic into a function. This makes the render function code a lot easier to understand, refactor, reuse, test, and think about.\n\n## Introduction\n\nConditional rendering is when a logical operator determines what will be rendered. The following code is from the examples in the official ReactJS documentation. It is one of the simplest examples of conditional rendering that I can think of.\n\n"
const headings = md
    .replaceAll(/```(.|\n)+```/gm, "")
    .split("\n")
    .filter(line => line.startsWith("#"))
console.log("Headings:", headings)