javascript - 用户代理移动设备无法正常工作

Question

因此，使用以下代码，无论我的用户代理是移动用户还是普通浏览器，当我仅在用户使用移动浏览器时运行该代码时，它都会继续执行 JQuery 代码。

        <script type="text/javascript">
window.mobilecheck = function() {
var check = false;
(function(a){if(/(android|bb\d+|meego).+mobile|avantgo|bada\/|blackberry|blazer|compal|elaine|fennec|hiptop|iemobile|ip(hone|od)|iris|kindle|lge |maemo|midp|mmp|mobile.+firefox|netfront|opera m(ob|in)i|palm( os)?|phone|p(ixi|re)\/|plucker|pocket|psp|series(4|6)0|symbian|treo|up\.(browser|link)|vodafone|wap|windows ce|xda|xiino/i.test(a)||/1207|6310|6590|3gso|4thp|50[1-6]i|770s|802s|a wa|abac|ac(er|oo|s\-)|ai(ko|rn)|al(av|ca|co)|amoi|an(ex|ny|yw)|aptu|ar(ch|go)|as(te|us)|attw|au(di|\-m|r |s )|avan|be(ck|ll|nq)|bi(lb|rd)|bl(ac|az)|br(e|v)w|bumb|bw\-(n|u)|c55\/|capi|ccwa|cdm\-|cell|chtm|cldc|cmd\-|co(mp|nd)|craw|da(it|ll|ng)|dbte|dc\-s|devi|dica|dmob|do(c|p)o|ds(12|\-d)|el(49|ai)|em(l2|ul)|er(ic|k0)|esl8|ez([4-7]0|os|wa|ze)|fetc|fly(\-|_)|g1 u|g560|gene|gf\-5|g\-mo|go(\.w|od)|gr(ad|un)|haie|hcit|hd\-(m|p|t)|hei\-|hi(pt|ta)|hp( i|ip)|hs\-c|ht(c(\-| |_|a|g|p|s|t)|tp)|hu(aw|tc)|i\-(20|go|ma)|i230|iac( |\-|\/)|ibro|idea|ig01|ikom|im1k|inno|ipaq|iris|ja(t|v)a|jbro|jemu|jigs|kddi|keji|kgt( |\/)|klon|kpt |kwc\-|kyo(c|k)|le(no|xi)|lg( g|\/(k|l|u)|50|54|\-[a-w])|libw|lynx|m1\-w|m3ga|m50\/|ma(te|ui|xo)|mc(01|21|ca)|m\-cr|me(rc|ri)|mi(o8|oa|ts)|mmef|mo(01|02|bi|de|do|t(\-| |o|v)|zz)|mt(50|p1|v )|mwbp|mywa|n10[0-2]|n20[2-3]|n30(0|2)|n50(0|2|5)|n7(0(0|1)|10)|ne((c|m)\-|on|tf|wf|wg|wt)|nok(6|i)|nzph|o2im|op(ti|wv)|oran|owg1|p800|pan(a|d|t)|pdxg|pg(13|\-([1-8]|c))|phil|pire|pl(ay|uc)|pn\-2|po(ck|rt|se)|prox|psio|pt\-g|qa\-a|qc(07|12|21|32|60|\-[2-7]|i\-)|qtek|r380|r600|raks|rim9|ro(ve|zo)|s55\/|sa(ge|ma|mm|ms|ny|va)|sc(01|h\-|oo|p\-)|sdk\/|se(c(\-|0|1)|47|mc|nd|ri)|sgh\-|shar|sie(\-|m)|sk\-0|sl(45|id)|sm(al|ar|b3|it|t5)|so(ft|ny)|sp(01|h\-|v\-|v )|sy(01|mb)|t2(18|50)|t6(00|10|18)|ta(gt|lk)|tcl\-|tdg\-|tel(i|m)|tim\-|t\-mo|to(pl|sh)|ts(70|m\-|m3|m5)|tx\-9|up(\.b|g1|si)|utst|v400|v750|veri|vi(rg|te)|vk(40|5[0-3]|\-v)|vm40|voda|vulc|vx(52|53|60|61|70|80|81|83|85|98)|w3c(\-| )|webc|whit|wi(g |nc|nw)|wmlb|wonu|x700|yas\-|your|zeto|zte\-/i.test(a.substr(0,4))) check = true;})(navigator.userAgent||navigator.vendor||window.opera);
return check;
};
if(window.mobilecheck){ //If mobile is True run this JQuery Code

    // create jump menu for mobile
    (function($) {
      $(document).ready(function() {
        $('ul.menu').each(function(){
          var list=$(this),
          select=$(document.createElement('select')).insertBefore($(this).hide()).change(function(){
            window.location.href=$(this).val();

          });
          $('>li a', this).each(function(){
            var option=$(document.createElement('option'))
              .appendTo(select)
              .val(this.href)
               .html($(this).html());
               select.addClass('menu')
            if($(this).attr('class') === 'selected'){
              option.attr('selected','selected');

            }
          });
          list.remove();
        });
      });
    })(jQuery);

} //End if mobile check
    </script>

Answer 1

window.mobilecheck 是一个函数，但您没有在 if 语句中调用它。

上面，您的代码如下所示:

window.mobilecheck = function() {
  //Your code here...
};

if (window.mobilecheck) {
  //This code will always run because window.mobilecheck is truthy.
}

但是，如果您将代码更改为如下所示:

//Call the function here.
if (window.mobilecheck()) {
  //This will only run if the return value is true.
}

您需要获取 mobilecheck 的值，但只有调用该函数才能做到这一点。

从风格上讲，我更喜欢将值放入变量中，并且可能放在稍后可以轻松检索该值的地方。:

var isMobile = window.isMobile = window.mobilecheck();
if (isMobile) {
  //Do stuff here...
}

请参阅代码片段，了解与您的问题相关的 JavaScript 中真假检查的示例。

(function() {

  'use strict';
  
  //Do a falsey check to see if the mobile function is defined.
  if (!window.mobilecheck) {
    document.write("Something's not right...");
  }
  
  window.mobilecheck = function mobileCheck() {
    //Do stuff here...
    var isMobile = true;
    return isMobile;
  };
  
  //This will always run because window.mobilecheck has been defined.
  if (window.mobilecheck) {
    document.write("<br />Mobile check has been defined");
  }
  
  var isMobile = window.mobilecheck();
  //We've retrieved the value from mobilecheck now.
  if (isMobile) {
    document.write("<br />This is a mobile device");  
  } else {
    document.write("This is not a mobile device");  
  }

})();

我希望这会有所帮助。