angularjs onload点击表列字段

<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.7.9/angular.min.js"></script>

<div ng-app="myApp" ng-controller="myController">
  <table>
    <tr>
      <th ng-click="sortBy('fieldName')">字段名称</th>
    </tr>
    <tr ng-repeat="item in items | orderBy:sortField">
      <td>{{item.fieldName}}</td>
    </tr>
  </table>
</div>

var app = angular.module('myApp', []);

app.controller('myController', function($scope) {
  $scope.items = [
    { fieldName: '字段1' },
    { fieldName: '字段2' },
    { fieldName: '字段3' }
  ];

  $scope.sortField = '';

  $scope.sortBy = function(fieldName) {
    $scope.sortField = fieldName;
  };
});