<html><script src="https://cdn.staticfile.net/angular.js/1.6.9/angular.min.js"></script><body ng-app=""><input ng-keypress="count = count + 1" ng-init="count=0" /><h1>{{count}}</h1><p>此例将在每次按下输入字段中的键时，增加变量“count”的值。</p></body></html>