Javascript AngularJS按钮ng单击不工作

Javascript AngularJS按钮ng单击不工作,javascript,html,angularjs,Javascript,Html,Angularjs,index.html <!DOCTYPE html> <html ng-app="todoApp"> <head> <title>To Do List</title> <link href="skeleton.css" rel="stylesheet"/> <script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.4.7/angular.

index.html

 <!DOCTYPE html>
<html ng-app="todoApp">
<head>
  <title>To Do List</title>
  <link href="skeleton.css" rel="stylesheet"/>
  <script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.4.7/angular.min.js"></script>
  <script src="app.js"></script>
</head>
<body ng-controller="todoController">
  <div class="section hero">
    <div class="container">
      <div class="row">
        <div class="three columns">
            <li>
              <button class="button button-primary" ng-click="btnClick(first)">Data 1</button>
            </li>
        </div>
        <div class="nine columns">
          <h4>{{dataText}}</h4>
        </div>
      </div>
    </div>
  </div>
</body>
</html>

当我单击按钮时,我希望ng click启动并调用控制器中的函数,但当我单击nothing时,屏幕上的文本不会改变或发生任何变化。我做错了什么?

html中没有名为first的变量

 <li>
   <button class="button button-primary" ng-click="btnClick(first)">Data 1</button>
 </li>

这是工作流程

什么是“第一”参考?ng click=“btnClick(first)”哦,我想让它传递一个类似“first”的字符串在这种情况下使用ng click=“btnClick('first')”我只是将其更改为该字符串,但由于某种原因它仍然不起作用。
 <li>
   <button class="button button-primary" ng-click="btnClick(first)">Data 1</button>
 </li>
 <li>
   <button class="button button-primary" ng-click="btnClick('first')>Data 1</button>
 </li>
  $scope.btnClick = function (num){
    $scope.dataText = "This is data from the " + num + " button."
  };