How Can I Retrieve GET Parameters in JavaScript?

Retrieving GET Parameters from JavaScript: A Detailed Guide

To retrieve GET parameters from within a JavaScript script, developers can leverage the window.location object. This object provides access to the current URL, including its query string.

One method to obtain GET parameters is by extracting the portion of the URL following the question mark (?). The following code snippet demonstrates this approach:

const getParams = () => {
  const searchParams = window.location.search.substr(1);  // Remove the question mark
  return searchParams;  // Return the GET parameters as a string
};

In the example provided, the GET parameter "returnurl" can be accessed using the following code:

const returnurl = getParams().split("=").pop();  // Extract the parameter value
console.log(returnurl);  // Log the parameter value to the console

However, this basic approach does not account for scenarios where multiple values are associated with the same parameter name. To handle such cases, a more robust solution is required.

The following enhanced function provides a comprehensive method to retrieve GET parameters, even when multiple values are present:

const findGetParameter = (parameterName) => {
  const result = null;
  const searchString = location.search.substr(1);
  const items = searchString.split("&");
  for (let index = 0; index < items.length; index++) {
    const [key, value] = items[index].split("=");
    if (key === parameterName) result = decodeURIComponent(value);
  }
  return result;
};

This function decodes the parameter value to ensure compatibility with special characters. It utilizes a for loop to iterate over each key-value pair in the query string. When the provided parameter name is found, the corresponding value is returned.

Using the function, the "returnurl" parameter can be obtained as follows:

const returnurl = findGetParameter("returnurl");
console.log(returnurl);

By leveraging these techniques, developers can effectively retrieve GET parameters from within JavaScript scripts, enhancing the functionality of web applications.

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