javascript - 未捕获的TypeError:$ .get(…)。则不是函数

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

<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>

最佳答案

尝试使用-

<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>