javascript - 正则表达式在 JS 文件中查找第一条评论

Question

我正在尝试编写一个正则表达式(用 JavaScript)来匹配 JS 文件开头的多行注释。

到目前为止，我想到了这个:/^(\/\*[^\*\/]*\*\/)/g

它适用于单行注释:http://refiddle.com/24o
但我的问题是它不适用于多行注释:http://refiddle.com/24m

你有什么解决办法吗？

Answer 1

赞HTML , JavaScript 不能被正则表达式解析。尝试正确地这样做是徒劳的。

相反，您必须使用能够将 JavaScript 源代码正确转换为 AST 的解析器，您可以通过编程方式检查它。幸运的是，有图书馆 do the parsing for you .

Here's a working example that outputs the AST of this code:

/* this is a
multi-line
comment */

var test = "this is a string, /* and this is not a comment! */";

// ..but this is

这让我们:

[
  "toplevel",
  [
    [
      {
        "name": "var",
        "start": {
          "type": "keyword",
          "value": "var",
          "line": 5,
          "col": 4,
          "pos": 57,
          "endpos": 60,
          "nlb": true,
          "comments_before": [
            {
              "type": "comment2",
              "value": " this is a\n    multi-line\n    comment ",
              "line": 1,
              "col": 4,
              "pos": 5,
              "endpos": 47,
              "nlb": true
            }
          ]
        },
        "end": {
          "type": "punc",
          "value": ";",
          "line": 5,
          "col": 67,
          "pos": 120,
          "endpos": 121,
          "nlb": false,
          "comments_before": []
        }
      },
      [
        [
          "test",
          [
            {
              "name": "string",
              "start": {
                "type": "string",
                "value": "this is a string, /* and this is not a comment! */",
                "line": 5,
                "col": 15,
                "pos": 68,
                "endpos": 120,
                "nlb": false,
                "comments_before": []
              },
              "end": {
                "type": "string",
                "value": "this is a string, /* and this is not a comment! */",
                "line": 5,
                "col": 15,
                "pos": 68,
                "endpos": 120,
                "nlb": false,
                "comments_before": []
              }
            },
            "this is a string, /* and this is not a comment! */"
          ]
        ]
      ]
    ]
  ]
]

现在只需遍历 AST 并提取您需要的内容即可。