Question

我想将表单中的username输入传递给socket.emit params。但是，当我进入socket.on function时，userName未定义。它应该是范围问题，而我不知道如何解决这个问题。我省略了一些代码来简化问题。没有必要让代码可运行，我只是想让方法如何处理这个问题。

＆＃13;

$("button").click(function (event) {
    event.preventDefault();
    setUserName($("input[name=name]").val());
});

var userName;

function setUserName(userName2) {
   userName=userName2;
}

var socket = io();

socket.on('connect', function () {
  var params = {
      name:userName
  }

  socket.emit('join', params, function (err) {
    
  });
});

＆＃13;

<body class="centered-form">
  <div class="centered-form__form">
    <form>
      <div class="form-field">
        <label>Display name</label>
        <input type="text" name="name" autofocus/>
      </div>
      <div class="form-field">
        <button id="submit">Submit</button>
      </div>
    </form>
  </div>
</body>
<script src="/libs/jquery-3.1.0.min.js"></script>
<script src="/chat.js"></script>

＆＃13;

Answer 1

您遇到了userName

的范围问题

＆＃13;

$("button").click(function (event) {
    event.preventDefault();
    setUserName($("input[name=name]").val());
});

var userName;

function setUserName(userName) {
  //this refers to the scope of the function
   this.userName=userName;
}

var socket = io();

socket.on('connect', function () {
  var params = {
      //this refers to the scope of the socket
      name:this.userName
  }

  socket.emit('join', params, function (err) {
    
  });
});

＆＃13;

尝试

＆＃13;

$("button").click(function (event) {
    console.log('__BUTTON_EVENT__');
    event.preventDefault();
    
    let name = $("input[name=name]").val();
    console.log('__USER_NAME__: ', name);
    setUserName(name);
});

var userName;

function setUserName(name) {
   userName = name;
}

var socket = io();

socket.on('connect', function () {
  var params = {
      name:userName
  }
  console.log('__CONNECTING__: ', params.name);

  socket.emit('join', params, function (err) {
    
  });
});

＆＃13;

如何在socket.emit parms

1 个答案: