用于删除字符串中字符开头到结尾的正则表达式

Question

我有这个字符串：

var string = "From: Jeremy<br />
 Sent: 22 Apr 2016 12:08:03</br />
 To: Mark<br />
 Subject: Another test email<br /><br />

 Hi Mark, 
<br />
I'm sending this email as a way to test the email! 
<br />
Cheers, 
<br />
Jeremy"

我想从头开始拼接这个字符串，直到 "Subject" 行之后，这样我才能得到电子邮件正文内容。

到目前为止我已经试过了：

string.substring(string.lastIndexOf('Subject'), string.length - 1)

但是这个选项 return 主题行也来自字符串。

有我可以使用的正则表达式库吗？

Answer 1

使用string.replace你可以做到：

var body = string.replace(/^[\s\S]*\s+Subject: [^\n]*\n+/, '')

代码：

var string = `From: Jeremy<br />
Sent: 22 Apr 2016 12:08:03</br />
To: Mark<br />
Subject: Another test email<br /><br />

Hi Mark, 
<br />
I'm sending this email as a way to test the email! 
<br />
Cheers, 
<br />
Jeremy`

var body = string.replace(/^[\s\S]*\s+Subject: [^\n]*\n+/, '')

document.writeln("<pre>" + body + "</pre>")

[\s\S]* 匹配 0 个或多个任意字符，包括换行符。紧随其后的 Subject: 行也被删除。

输出：

"Hi Mark, 
<br />
I'm sending this email as a way to test the email! 
<br />
Cheers, 
<br />
Jeremy"

Answer 2

有人会给你非正则表达式的解决方案，但这里有一个带有正则表达式的解决方案

[\s\S]*Subject\s*:.*([\s\S]+) <-- your result in first capturing group

Regex Demo

JS 演示

var re = /[\s\S]*Subject\s*:.*([\s\S]+)/gm; 
var str = `From: Jeremy<br />
Sent: 22 Apr 2016 12:08:03</br />
To: Mark<br />
Subject: Another test email<br /><br />

Hi Mark, 
<br />
I'm sending this email as a way to test the email! 
<br />
Cheers, 
<br />
Jeremy`
var m = re.exec(str);
document.writeln("<pre>" + m[1] + "</pre>");

用于删除字符串中字符开头到结尾的正则表达式

Regex expression to remove start to end of character in string

javascript

regex

substring

splice