正则表达式在浏览器中不起作用

Question

正则表达式位于rubular页面中且完美运行：http://rubular.com/r/vtflEgDdkY

但在本地主持人中，我无法使用它...... 这是我的代码

var file = readTextFile("story.txt") // not empty
var result = file.match(/(::head.*?$^.*?$)^\s*$/m)

console.log(result) // writes null

file 变量不为空且readTextFile（）函数正在运行。

这是story.txt

::head
line 1
line 2
line 3

::content
content 1
content 2
content 3 

正则表达式无法正常工作......问题出在哪里？

Answer 1

描述

如果您希望同时捕获头部和内容，可以使用此表达式

::head\n((?:(?!\n+::).)*)\n+::content\n((?:(?!\n+::).)*)$

实施例

现场演示

https://regex101.com/r/oX8vR6/1

示例文字

::head
line 1
line 2
line 3

::content
content 1
content 2
content 3 

样本匹配

• 捕获组1获取head
中的值
• 捕获组2获取content
中的值

1.  [7-27]  `line 1
line 2
line 3`

2.  [39-69] `content 1
content 2
content 3 `

Javascript代码示例：

<script type="text/javascript">
  var re = /::head[\r\n]((?:(?![\r\n]+::).)*)[\n\r]+::content[\r\n]((?:(?![\r\n]+::).)*)$/;
  var sourcestring = "  ---- your sample text goes here ----  ";
  var results = [];
  var i = 0;
  for (var matches = re.exec(sourcestring); matches != null; matches = re.exec(sourcestring)) {
    results[i] = matches;
    for (var j=0; j<matches.length; j++) {
      alert("results["+i+"]["+j+"] = " + results[i][j]);
    }
    i++;
  }
</script>

示例输出

$matches Array:
(
    [0] => Array
        (
            [0] => ::head
line 1
line 2
line 3

::content
content 1
content 2
content 3 
        )

    [1] => Array
        (
            [0] => 
line 1
line 2
line 3
        )

    [2] => Array
        (
            [0] => 
content 1
content 2
content 3 
        )

)

解释

NODE                     EXPLANATION
----------------------------------------------------------------------
  ::head                   '::head'
----------------------------------------------------------------------
  \n                       '\n' (newline)
----------------------------------------------------------------------
  (                        group and capture to \1:
----------------------------------------------------------------------
    (?:                      group, but do not capture (0 or more
                             times (matching the most amount
                             possible)):
----------------------------------------------------------------------
      (?!                      look ahead to see if there is not:
----------------------------------------------------------------------
        \n+                      '\n' (newline) (1 or more times
                                 (matching the most amount possible))
----------------------------------------------------------------------
        ::                       '::'
----------------------------------------------------------------------
      )                        end of look-ahead
----------------------------------------------------------------------
      .                        any character except \n
----------------------------------------------------------------------
    )*                       end of grouping
----------------------------------------------------------------------
  )                        end of \1
----------------------------------------------------------------------
  \n+                      '\n' (newline) (1 or more times (matching
                           the most amount possible))
----------------------------------------------------------------------
  ::content                '::content'
----------------------------------------------------------------------
  \n                       '\n' (newline)
----------------------------------------------------------------------
  (                        group and capture to \2:
----------------------------------------------------------------------
    (?:                      group, but do not capture (0 or more
                             times (matching the most amount
                             possible)):
----------------------------------------------------------------------
      (?!                      look ahead to see if there is not:
----------------------------------------------------------------------
        \n+                      '\n' (newline) (1 or more times
                                 (matching the most amount possible))
----------------------------------------------------------------------
        ::                       '::'
----------------------------------------------------------------------
      )                        end of look-ahead
----------------------------------------------------------------------
      .                        any character except \n
----------------------------------------------------------------------
    )*                       end of grouping
----------------------------------------------------------------------
  )                        end of \2
----------------------------------------------------------------------
  $                        before an optional \n, and the end of a
                           "line"
----------------------------------------------------------------------

Answer 2

怎么样：

var s = "::head\nline 1\nline 2\nline 3\n\n::content\ncontent 1\ncontent 2\ncontent 3\n\n";

var r = s.match(/(::head[\s\S]+?)\n\n/);
console.log(r);

<强>输出：

["::head\nline 1\nline 2\nline 3\n\n", "::head\nline 1\nline 2\nline 3"]