如果需要条件-测试属性是否存在（如果不存在），然后创建一个

Question

Below is some code that overwrites a property in a string but what is missing in this function is a condition to test if the property exists and if it doesn't then create it and then return the whole string, otherwise overwrite the property and return then whole string which it does at the moment. I have attempted this but I'm not getting the desired result. Can someone have a look and attempt to create a new property on the fly with the sample function below.

var cookieValue = 
   'id=1&state=normal&theme=purple:
    id=2&state=maximized&theme=pink:
    id=3&state=maximized&theme=black';

function setProperties(cookie, id , name, value, create) {
  var sections = $.map(cookie.split(":"), function (section) {
      var pairs;

      if (section.indexOf("id=" + id) === 0) {
          // if condition here - create a new property
          // else run code below
          pairs = $.map(section.split("&"), function (pair) {
              if (pair.indexOf(name + "=") === 0) {
                  return name + "=" + value;
              }else {                       
                  return pair;  
              }
          });

          return pairs.join("&");

      } else {
          return section;
      }
  });

  return sections.join(":");
}
alert(setProperties(cookieValue, '2', 'theme', 'green', true));
alert(setProperties(cookieValue, '2', 'color', 'orange', true)); // new property

Answer 1

Just remember if you have found the property:

      if (section.indexOf("id=" + id) === 0) {
        // if condition here - create a new property
        // else run code below
        var found = false;
        pairs = $.map(section.split("&"), function (pair) {
            if (pair.indexOf(name + "=") === 0) {
                return name + "=" + value;
                found = true;
            } else {                       
              return pair;  
            }
        });

        section = pairs.join("&");
        if (!found) {
            section += "&" + name + "=" + value;
        }
    }
    return section; 

If a property exists then found will be set to true. Otherwise the property is appended to the section. Working fiddle