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PHP Regular Expressions: How to match all JavaScript functions in HTML

WBOYOriginal: 2023-06-22 19:03:54917browse

In front-end development, we often need to use JavaScript to achieve dynamic interactive effects on the page. In HTML pages, we usually define JavaScript functions in the 3f1c4e4b6b16bbbd69b2ee476dc4f83a tag, and use the browser's parsing capabilities to execute these functions. Sometimes, we need to extract all JavaScript functions from the HTML page and perform some processing on them, such as analyzing the code structure of the function, finding the calling location of the function, modifying the implementation of the function, etc. At this time, we can use PHP regular expressions to match JavaScript functions in HTML code.

So, how to use PHP regular expressions to match all JavaScript functions in HTML? The following is a simple example:

<?php
$html = '<html>
            <head>
                <title>My HTML Page</title>
                <script>
                    function hello() {
                        alert("Hello, world!");
                    }
                </script>
            </head>
            <body>
                <script>
                    function greet(name) {
                        alert("Hello, " + name + "!");
                    }
                </script>
                <p>Welcome to my HTML page!</p>
            </body>
        </html>';

// 定义正则表达式
$pattern = '/<script>s*functions+(w+)s*((.*?))s*{([sS]*?)}s*</script>/i';

// 进行匹配
preg_match_all($pattern, $html, $matches);

// 输出匹配结果
foreach ($matches[1] as $index => $function) {
    echo "Function $function:<br>";
    echo $matches[0][$index] . "<br><br>";
}
?>

In the above example, an HTML code string $html containing a JavaScript function is first defined, and then a regular expression is defined $pattern, used to match all JavaScript functions in it. The explanation of this regular expression is as follows:

3f1c4e4b6b16bbbd69b2ee476dc4f83a: matches the beginning of the 3f1c4e4b6b16bbbd69b2ee476dc4f83a tag;
s*: matches zero or more whitespace characters;
function: matches the function keyword;
s : Match one or more whitespace characters;
(w): Match the function name, where w represents any letter, number or underscore ;
s*: Match zero or more whitespace characters;
((.*?)): Match function parameter list, Among them, (.*?) means matching any character in non-greedy mode;
s*: matches zero or more whitespace characters;
{([sS]*?)}: Matching function body, where [sS]*? indicates non-greedy mode matching of any characters, including newlines and spaces;
s*2cacc6d41bbb37262a98f745aa00fbf0: Matches the end of the 3f1c4e4b6b16bbbd69b2ee476dc4f83a tag.

Next, we use the preg_match_all function to match the JavaScript functions in $html. The parameters of this function are the regular expression, the string to be matched, and the matching result array. Finally, we output the matching results by traversing the function names and function bodies in the matching results.

It should be noted that in actual applications, we also need to use some methods to process the matched JavaScript functions, such as replacing the variable names in the function body, extracting the function call location, etc., to meet specific needs.

In the actual development process, we can adjust the matching rules of regular expressions according to different situations to obtain more accurate matching results. In addition, regular expressions are less efficient and may have a certain impact on program performance, so they need to be used and optimized with caution.

The above is the detailed content of PHP Regular Expressions: How to match all JavaScript functions in HTML. For more information, please follow other related articles on the PHP Chinese website!

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