静态：
<view class='num'>
<view class='buy'>购买数量</view>
<view class='goods'>
<button
bindtap='jian' class='jian'
data-num='{{num}}'>-</button>
<input name='num'
bindchange='num' type='text'
value='{{num}}'/>
<button
bindtap='jia' class='jia'
data-num='{{num}}'>+</button>
<view class='clear'></view>
</view>
<view class='clear'></view>
</view>
js:
page({
data:{
num:1,
}
jia:function(e){
var num = e.currentTarget.dataset.num;
num ++;
this.setData({num:num})
},
jian: function (e) {
var num = e.currentTarget.dataset.num;
if(num>1){
num--;
}
this.setData({ num: num })
},
num:function(e){
var num= e.detail.value;
this.setData({num:num});
},
})