微信小程序报错(1) (in promise) MiniProgramError Cannot read property ‘findIndex‘ of null TypeError: Cannot

1、 微信小程序报这类错误:

(in promise) MiniProgramError Cannot read property ‘findIndex’ of null TypeError: Cannot read property ‘findIndex’ of null
data: {
    addval:"",
    editval:"",
    typeList:[]
  },
  // 添加
  async add(){
    let typeName = this.data.addval
    // 判断分类名称是否重复
    // console.log(this.data.typeList);
    const index = this.data.typeList.findIndex(item => {
      return item.typeName == typeName
    })
问题所在:

发现当typeList中的值为空时,就会报这个错误,有 数据时就不会报错

解决办法:

在循环之前加一个判断

 **this.data.typeList= this.data.typeList || [ ]**
 
    // 判断分类名称是否重复
      var index = this.data.typeList.findIndex(item => {
        return item.typeName == typeName
      })

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