Uncaught TypeError：$ .get（...）。然后不是函数

Question

这是我的代码..我在控制台收到错误Uncaught TypeError：$ .get（...）。然后不是函数..error是在第18次线

<button class="btn btn-primary" id="requestButton">HTTP Request</button> 
<ul id="myList"></ul> 
<script type="text/javascript"> 
    var ulElm = document.querySelector("#myList"); 
    var first = false; 
    var chatList; 
    function updateChat() { 
     console.log("update Chat called"); 
     $.get("http://projecttester.16mb.com/makejson.php") 
     .then(function(data) {//ERROR IS IN THIS LINE 
      if(!first) { 
       chatList = JSON.parse(data); 
       chatList.forEach(function(item) { 
        var liElm = document.createElement('li'); 
        liElm.innerHTML = item.Message; 
        ulElm.appendChild(liElm); 
       }); 
</script> 
</body> 

Answer 1

尝试使用此 -

<button class="btn btn-primary" id="requestButton">HTTP Request</button> 
<ul id="myList"></ul> 
<script type="text/javascript"> 
    var ulElm = document.querySelector("#myList"); 
    var first = false; 
    var chatList; 
    function updateChat() { 
     console.log("update Chat called"); 
     $.get("http://projecttester.16mb.com/makejson.php", function(data) { 
      if(!first) { 
       chatList = JSON.parse(data); 
       chatList.forEach(function(item) { 
        var liElm = document.createElement('li'); 
        liElm.innerHTML = item.Message; 
        ulElm.appendChild(liElm); 
       } 
      } 
     }); 
    } 
</script> 
</body>