JS small method

(function () {
    
  //  Remove the spaces at the left and right ends of the string 
  String.prototype.trim = function () {
    
    return this.replace(/(^\s*)|(\s*$)/g, "");
  };

  // // Remove the space on the left 
  String.prototype.ltrim = function () {
    
    return this.replace(/(^\s*)/g, "");
  };

  // Remove the space on the right 
  String.prototype.rtrim = function () {
    
    return this.replace(/(\s*$)/g, "");
  };

  //  It can be written as a function like this ：(trim(str))
  function trim(str) {
    
    // Delete the left and right spaces 
    return str.replace(/(^\s*)|(\s*$)/g, "");
  }
  function ltrim(str) {
    
    // Remove the space on the left 
    return str.replace(/(^\s*)/g, "");
  }
  function rtrim(str) {
    
    // Remove the space on the right 
    return str.replace(/(\s*$)/g, "");
  }
})();

// ajax Encapsulation 
function createXhr() {
    
  if (typeof XMLHttpRequest != undefined) {
    
    return new XMLHttpRequest();
  } else {
    
    var xhr = null;

    try {
    
      xhr = new ActiveXObject("MSXML2.XmlHttp.6.0");
      return xhr;
    } catch (e) {
    
      try {
    
        xhr = new ActiveXObject("MSXML2.XmlHttp.3.0");
        return xhr;
      } catch (e) {
    
        throw Error(" Your broken browser does not support ajax");
      }
    }
  }
}

/*****************ajax ******************/
// The first method ：ajax  Encapsulation of functions 
/** * ajax: async javascript and xml / json *  Asynchronous JavaScript  and  xml / json {} *  purpose ：  Data interaction  （ Network request ） * XMLHTTPRequest() * * *  Simple request ajax： * 1.  Request mode ： get / post / head * 2.  Request header information ：  Can only contain ： * Accept: * Accept-Encoding: gzip, deflate, br Accept-Language: zh-CN,zh;q=0.9 Connection: keep-alive Host: 127.0.0.1:5501 If-Modified-Since: Tue, 27 Aug 2019 11:48:43 GMT If-None-Match: W/"6f2-16cd2e81e70" Referer: http://127.0.0.1:5501/view/index.html Sec-Fetch-Mode: cors Sec-Fetch-Site: same-origin User-Agent: Content-Type: application/x-www-form-urlencode ; multipart/form-data; text/plain; * * method:  Request mode  get * url:  Requested address  * callback:  Callback function  success:  Successful callback function  * data:  Request data （ Request parameters ） * falg:  Asynchronous or not  * isAsync:  Asynchronous or not  true * * headers : {} * @param { Object } options * */
function ajax(options) {
    
  // var xhr = new XMLHttpRequest();
  var xhr = null;
  if (window.XMLHttpRequest) {
    
    xhr = new XMLHttpRequest();
  } else if (window.ActiveXObject) {
    
    xhr = new ActiveXObject("Microsoft.XMLHTTP");
  } else {
    
    return alert(" The current browser does not support XMLHTTPRequest");
  }
  var method = "";
  var data = "";
  var isAsync = typeof options.isAsync === "undefined" ? true : options.isAsync;
  var url = options.url;
  var success =
    typeof options.success === "function" ? options.success : function () {
    };
  if (options.method) {
    
    method = options.method.toUpperCase();
  } else {
    
    method = "GET";
  }
  // 0 - 4
  xhr.onreadystatechange = function () {
    
    if (xhr.readyState === 4) {
    
      if (xhr.status === 200) {
    
        success(JSON.parse(xhr.responseText));
      }
    }
  };
  if (typeof options.data === "object") {
    
    for (var prop in options.data) {
    
      data += prop + "=" + options.data[prop] + "&";
    }
    data = data.slice(0, data.length - 1);
  } else {
    
    data = options.data;
  }
  if (options.method === "GET") {
    
    xhr.open(method, url + "?" + data, isAsync);
    xhr.send();
  } else {
    
    //  Establishing a connection 
    xhr.open(method, url, isAsync);
    xhr.setRequestHeader("Content-type", "application/x-www-form-urlencode");
    // key=value&key1=value
    //  Sending data 
    xhr.send(data);
  }
}

/****************************************/
// The second method ：ajax  Encapsulation of functions 
function ajax(opts) {
    
  var set = extend(
    {
    
      url: "",
      data: "",
      type: "GET",
      timeout: 5000,
      onbeforerequest: function () {
    }, // Before sending the request 
      onsuccess: function () {
    }, // Data accepted successfully 
      onnottmodified: function () {
    }, // The data has not changed 
      onfailure: function () {
    }, // request was aborted 
    },
    opts || {
    }
  );

  var xhr = createXhr();

  if (set.type.toUpperCase() == "GET") {
    
    // Decide whether to add cache ？ Add one date character string , Prevent caching ( When there is a cache , The request is no longer sent to the backend , Read local directly )
    if (set.data) {
    
      set.url += (set.url.indexOf("?") >= 0 ? "&" : "?") + "t=" + +new Date();
    }
  }

  //  whenever  readyState  When the change , It will trigger  onreadystatechange  event 
  //  State detection 
  xhr.onreadystatechange = function () {
    
    if (xhr.readyState == 4) {
    
      // Callback function 
      set.onsuccess.call(xhr);
      if (xhr.status >= 200 && hr.status < 300) {
    
      } else if (xhr.status == 304) {
    
        set.onnottmodified.call(xhr);
      } else {
    
        set.onfailure.call(xhr);
      }
    }

    //  Open the link 
    xhr.open(set.type, set.url);

    if (set.type.toUpperCase() == "POST") {
    
      xhr.setRequestHeader("content-Type", "application/x-www-form-urlencoded");
    }

    // This function will call back by itself , Usually this step is useless 
    set.onbeforerequest();

    // Timeout reset time 
    if (set.timeout) {
    
      setTimeout(function () {
    
        xhr.onreadystatechange = function () {
    };
        xhr.abort();
        set.onfailure();
      }, set.timeout);
    }

    //  This step is to send data , The back-end server will receive 
    xhr.send(set.data);
  };
}
/****************************************/