How to extract 'label_name' from HTML using regular expressions and implement output in JavaScript and PHP?

Efficiently extract HTML data: Detailed explanation of regular expression application

Extracting specific information from lengthy HTML code is a common task in web page data processing. This article will explain in detail how to use regular expressions to accurately extract target content in HTML, and provide JavaScript and PHP code examples to solve the problem of extracting "label_name":"历史" from the specified URL (where "history" is a variable).

Regular expression extracts target fields

Assuming that the HTML snippet contains "label_name":"历史" we can efficiently extract the field with regular expressions. The following JavaScript code demonstrates how to implement it:

 const str = 'shflehoshofwe"label_name":"History"lshdliflwefoiewoilfjnwo';
const regex = /"label_name":"(. ?)"/;
const match = str.match(regex);

if (match) {
  const value = match[0];
  console.log(value); // Output: "label_name":"History"
} else {
  console.log("No match found");
}

Regular expression /"label_name":"(. ?)"/ matches the contents after "label_name":" , (. ?) uses non-greedy matching ( ? ), ensuring that only contents between the next double quotes are extracted.

PHP code to implement web page data extraction

If you need to get HTML content from the specified URL and then extract it, you can use PHP code:

 $url = 'Specified URL';
$html = file_get_contents($url);

preg_match('/"label_name":"(. ?)"/', $html, $match);

if ($match) {
  echo $match[0]; // Output: "label_name":"History"
} else {
  echo "No match found";
}

This code first uses file_get_contents() to get the HTML content of the specified URL, and then uses preg_match() function to perform regular expression matching and output the matched result.

Summarize

Through the above JavaScript and PHP code examples, we can easily extract target fields such as "label_name":"历史" from HTML, and can be extracted accurately even if the "History" part is dynamically changed. Remember, in practice, adjust regular expressions according to the specific HTML structure to ensure the accuracy of the extraction. Furthermore, for complex HTML structures, it is recommended to use a more powerful HTML parser instead of relying solely on regular expressions.

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