正則運算式-從降價字串中提取所有標題

我正在使用灰質將檔案系統中的 .MD 檔案決議為字串。決議器產生的結果是這樣的字串：

\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

我現在正在嘗試撰寫一個從字串中提取所有標題文本的正則運算式。markdown 中的標題以 # 開頭（可以是 1-6），在我的情況下總是以新行結尾。

我嘗試使用以下正則運算式，但在我的測驗字串上呼叫它不會回傳任何內容：

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)?|\\n)/gm;
const headings = HEADING_R.exec(content);

console.log('headings: ', headings);

此控制臺記錄headings為null（未找到匹配項）。我正在尋找的結果是：["# Clean-er ReactJS Code - Conditional Rendering", "## TL;DR", "## Introduction"].

我相信正則運算式是錯誤的，但不知道為什么。

uj5u.com熱心網友回復：

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

• #{1,6}... 匹配字符#至少一次或作為最多 6 個相等字符的序列。

• . 匹配任何字符（行終止符除外）至少一次且盡可能多次（貪婪）

• 這樣做直到積極的前瞻 (?=\n)匹配......

  • 這是……\n換行符/換行符。

• 使用g匹配所有內容的 lobal 修飾符。

編輯

提到過

“匹配任何字符（行終止符除外）”

因此，像 ... /#{1,6}. /g... 這樣的正則運算式應該已經為 OP 的用例完成了這項作業（不需要積極的前瞻），即 ...

“markdown 中的標題以 # 開頭（可以是 1-6），在我的情況下總是以新行結尾。 ”

我正在尋找的結果是：["# 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; }

獎金

將上述正則運算式重構為例如/(?<flag>#{1,6})\s (?<content>. )/g通過使用命名捕獲組以及ping 任務，matchAll可以獲得map類似于下一個提供的示例代碼計算的結果......

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; }

uj5u.com熱心網友回復：

問題是您正在為正則運算式使用文字，并且不應雙重轉義反斜杠，因此您可以將其寫為 (?<!#)#{1,6} (.*?)(\r(?:\n)?|\n)

您可以縮短捕獲所需內容的模式并匹配尾隨換行符，而不是使用后向斷言。

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

檢索所有捕獲組 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);

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