1、下載後引入angular.min.js
2、程式碼如下：

<h1>計算商品價格</h1>
<div ng-app="buy" ng-controller="contro">
    <p>
        <button ng-click="decr()">-</button>
        <input type="text" ng-model="num" readonly>
        <button ng-click="incr()">+</button>
    </p
 
>
    <p>
        總價：{{num*8}}
    </p>
</div>
<script>
    var app = angular.module('buy' , []);
    app.controller('contro',function($scope){
        $scope.num=1;
        $scope.incr=function(){
            this.num += 1;
        }
        $scope.decr=function(){
            //只有大於一的時候才減
 

            if(this.num>1){
                this.num -= 1;
            }
        }
    });
</script>