微信小程序报错：this.setData is not a function的解决办法

<strong> pasteEncryptedText:function()</strong>{ 
 let decryptedPass = this.data.decryptedPassword; 
 if (decryptedPass == '' ){ 
 wx.showToast({ 
 title: '请先输入解密密码', 
 mask: true, 
 success: function (res) { 
  setTimeout(function () { 
  wx.hideToast(); 
  }, 4000); 
 }, 
 }); 
 return; 
 }else{ 
 wx.getClipboardData({ 
 <strong>success: function (res)</strong> { 
  if ( res.data == '' ){ 
  wx.showToast({ 
  title: '剪贴板没有内容', 
  mask: true, 
  success: function (res) { 
  setTimeout(function () { 
   wx.hideToast(); 
  }, 4000); 
  }, 
  }) 
  }else{ 
  console.log(decryptedPass); 
  console.log(res.data); 
  <strong>this.setData({ 
  encryptedTextDecode: res.data, 
  originalTextDecode: desEncryptedDecrypted.decrypt(res.data, decryptedPass), 
  });</strong> 
  console.log(this.data.originalTextDecode); 
  } 
 } 
 }); 
 } 
 } 

<strong> 在函数pasteEncryptedText()一开始处将this对象保存：</strong>let that = this; 

pasteEncryptedText:function(){ 
 let decryptedPass = this.data.decryptedPassword; 

<strong>let that = this;</strong> 
if (decryptedPass == '' ){ 
 wx.showToast({ 
 title: '请先输入解密密码', 
 mask: true, 
 success: function (res) { 
 setTimeout(function () { 
 wx.hideToast(); 
 }, 4000); 
 }, 
 }); 
 return; 
}else{ 
 wx.getClipboardData({ 
 success: function (res) { 
 if ( res.data == '' ){ 
 wx.showToast({ 
  title: '剪贴板没有内容', 
  mask: true, 
  success: function (res) { 
  setTimeout(function () { 
  wx.hideToast(); 
  }, 4000); 
  }, 
 }) 
 }else{ 
 console.log(decryptedPass); 
 console.log(res.data); 
 <strong> that.setData</strong>({ 
  encryptedTextDecode: res.data, 
  originalTextDecode: desEncryptedDecrypted.decrypt(res.data, decryptedPass), 
 }); 
 console.log(<strong>that.data.originalTextDecode</strong>); 
 } 
 } 
 }); 
}