How to extract a string of specific content such as 'label_name': 'history' from HTML code?

Regular expressions and implementation methods for extracting specific content in HTML

Problem description

During the process of learning programming, a friend of Xiaobai encountered a confusion: how to extract specific content from HTML code and ignore other irrelevant information. Specifically, he wants to extract a string similar to "label_name": "history", where "history" is the variable value and no other part is needed. Please help from all the big guys, I hope to provide regular expressions or PHP code to achieve this requirement.

Solution

To extract the specified content from the HTML code, we can use regular expressions to locate and extract strings like "label_name": "History". Here is a sample code using JavaScript that shows how to implement this functionality:

 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 string matched");
}

In this code, we define a regular expression /\"label_name\":\"(. ?)\"/, which is used to match strings such as "label_name":"History". . ? is a non-greedy match, indicating that any character is matched until the next double quote is encountered.

The workflow of the code is as follows:

1. Defines a variable str containing the target string.
2. Use the regular expression regex for matching.
3. If the match is successful, the entire matching string is obtained through match[0] and output it.
4. If it does not match, a prompt message is output.

In this way, with simple regular expressions and a few lines of code, we can extract what we need from the HTML code, ignoring other irrelevant information.

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