Javascript变量范围问题

Question

我有一个变量mutedUser,我想坚持到另一个函数.我在click事件之外持久存在变量时遇到了一些麻烦.拥有它的最佳方法是什么,以便"返回mutedUser"将根据if语句的条件保持"静音"字符串添加？谢谢!

*console.log是我检查持久性停止的位置

this.isUserMuted = function isUserMuted(payload) {
  var mutedUser = '';
  // If mute button is clicked place them into muted users list
  // check for duplicates in list
  $("#messages-wrapper").off('click', '.message button.muteButton');
  $("#messages-wrapper").on('click', '.message button.muteButton', function(e) {

      $('#unMute').show();

      //create userId reference variable
      var chatUserID = parseInt($(this).parent().parent().attr("data-type"));

      //store userId in muted user object
      mutedUsers[chatUserID] = {};
      mutedUsers[chatUserID].id = chatUserID;
      mutedUsers[chatUserID].muted = true;

      if (mutedUsers[chatUserID] !== null && mutedUsers[chatUserID].id === payload.a) {
          console.log("user is now muted");
          mutedUser += ' muted';
          console.log(mutedUser + 1);
      }
      console.log(mutedUser + 2);
  });
  return mutedUser;
};

Answer 1

如果我理解你要做的事情(通过查看代码),这将是最好的方法:

// If mute button is clicked place them into muted users list
// check for duplicates in list
$("#messages-wrapper").off('click', '.message button.muteButton');
$("#messages-wrapper").on('click', '.message button.muteButton', function(e) {
    $('#unMute').show();

    //create userId reference variable
    var chatUserID = parseInt($(this).parent().parent().attr("data-type"));

    //store userId in muted user object
    mutedUsers[chatUserID] = {};
    mutedUsers[chatUserID].id = chatUserID;
    mutedUsers[chatUserID].muted = true;
});

this.isUserMuted = function isUserMuted(payload) {
  var mutedUser = '';

  if (mutedUsers[payload.a] !== null) {
      mutedUser += ' muted';
  }

  return mutedUser;
};

如果提供的用户在该数组中mutedUsers,代码将保留数组和isUserMuted函数检查.在您提供的代码中,每次isUserMuted调用函数时都会附加一个新的事件处理程序.

该isUserMuted功能甚至可以缩短为:

this.isUserMuted = function isUserMuted(payload) {
  return mutedUsers[payload.a] !== null ? ' muted' : '';
};