<view>
  <text>{{str}}</text>
</view>
<button bindtap="change">改变</button>

Page({
 data: {
  str:'早上好'
 },
 change: function() {
  this.setData({
   str:"晚上好"
  })
 }
})

<view>
  <text>{{array[0].text}}</text>
</view>
<button bindtap="change">改变</button>

Page({
 data: {
  array: [{text: '早上好'}],
 },
 change: function() {
  this.setData({
   'array[0].text':'晚上好'
  })
 }
})

<view>
  <block wx:for="array" wx:key="index">
    <text>{{item.text}}</text>
    <button bindtap="change" data-index="index">改变</button>
  </block>
</view>
<button bindtap="change">改变</button>

Page({
  data:{
    array:[
      {text:'1111'},
      {text:'2222'},
      {text:'3333'}
    ]
  },
  change:function(e){
    let param = {};
    let string = "array["+e.target.dataset.index+"].text;
    param[string] = '0000';
    this.setData(param);
  }
})