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Regular replacement of html

PHPzOriginal: 2023-05-21 17:54:39503browse

Regular expressions are often used in daily code processing, and one of the common applications is to replace strings. In web development, we often need to replace some HTML tags or specific characters. So how do regular expressions achieve such a function? Let's introduce how to use regular expressions for HTML replacement.

What is a regular expression?

Regular Expression is a method of matching and searching strings and symbol sequences. model. In layman's terms, a regular expression is a rule that defines a pattern of strings. Regular expressions are not a programming language, but a set of rules invented by computer scientists and are now widely used in various programming languages. In JavaScript, we can use RegExp objects to represent regular expressions.

HTML Replacement Example

Now there is an HTML string that contains some unnecessary tags, and these tags need to be replaced. We can use regular expressions to accomplish this task. The following is an example:

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>HTML替换实例</title>
</head>
<body>
    <div class="content">
        <p>这是一段需要替换的HTML字符串，<span>其中包含一些需要被替换的标签</span>，比如<strong>这个标签</strong>，还有<a href="#">这个标签</a>，需要转化成纯文本格式。</p>
    </div>
</body>
</html>

Now you need to replace all the HTML tags in this page with plain text. You can use the following regular expression:

/<(?:.|\n)*?>/gm

Among them, 5d4d65d8636d296a6b20e38b224c12b5 represent the start and end marks of the tag, (?:.|\n)*? means matching 0 or more non-newline characters, where (?:) means not to capture the content of the group, gm is the modifier of the regular expression, g means global matching, m means multiple lines match.

Use JavaScript code to replace:

var htmlStr = 'HTML替换实例这是一段需要替换的HTML字符串，其中包含一些需要被替换的标签，比如这个标签，还有这个标签，需要转化成纯文本格式。';
var pureText = htmlStr.replace(/<(?:.|\n)*?>/gm, '');
console.log(pureText);

The running result is:

HTML替换实例这是一段需要替换的HTML字符串，其中包含一些需要被替换的标签，比如这个标签，还有这个标签，需要转化成纯文本格式。

As you can see, all HTML tags have been replaced with plain text.

Summary

In website development, using regular expressions for HTML replacement is a common requirement. Use regular expressions to replace strings quickly and efficiently. It should be noted that the symbols and modifiers in regular expressions may be different and need to be determined according to specific needs.

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