Get URL parameters from a given url such as query string in JavaScript

geturlPrameter.js

function getAllUrlParams(url) {
    // get query string from url (optional) or window
    var queryString = url ? url.split("?")[1] : window.location.search.slice(1);

    // we'll store the parameters here
    var obj = {};

    // if query string exists
    if (queryString) {
      // stuff after # is not part of query string, so get rid of it
      queryString = queryString.split("#")[0];

      // split our query string into its component parts
      var arr = queryString.split("&");

      for (var i = 0; i < arr.length; i++) {
        // separate the keys and the values
        var a = arr[i].split("=");

        // set parameter name and value (use 'true' if empty)
        var paramName = a[0];
        var paramValue = typeof a[1] === "undefined" ? true : a[1];

        // (optional) keep case consistent
        paramName = paramName.toLowerCase();
        if (typeof paramValue === "string")
          paramValue = paramValue.toLowerCase();

        // if the paramName ends with square brackets, e.g. colors[] or colors[2]
        if (paramName.match(/\[(\d+)?\]$/)) {
          // create key if it doesn't exist
          var key = paramName.replace(/\[(\d+)?\]/, "");
          if (!obj[key]) obj[key] = [];

          // if it's an indexed array e.g. colors[2]
          if (paramName.match(/\[\d+\]$/)) {
            // get the index value and add the entry at the appropriate position
            var index = /\[(\d+)\]/.exec(paramName)[1];
            obj[key][index] = paramValue;
          } else {
            // otherwise add the value to the end of the array
            obj[key].push(paramValue);
          }
        } else {
          // we're dealing with a string
          if (!obj[paramName]) {
            // if it doesn't exist, create property
            obj[paramName] = paramValue;
          } else if (obj[paramName] && typeof obj[paramName] === "string") {
            // if property does exist and it's a string, convert it to an array
            obj[paramName] = [obj[paramName]];
            obj[paramName].push(paramValue);
          } else {
            // otherwise add the property
            obj[paramName].push(paramValue);
          }
        }
      }
    }

    return obj;
  }