前端 - js 第二次赋值为空？

Question

代码如下：

methods: {
    submit(){

        this.tableData.forEach(sub => {
          sampleProcessList = sub.sampleProcessInfo.sampleProcessList
        })

      let sampleProcessListss = JSON.parse(JSON.stringify(sampleProcessList))
      sampleProcessListss.find(element => {
        if (element.id === this.input.selectSampleProcess) {
          this.processName = element.processName
        }
      })
      const idList = this.ids.map(i => i)

      this.tableData.forEach(v => {
        if (idList.includes(v.id)) {
          v.processName = this.processName
        }
      })
      console.log(this.processName);
      }
  }

问题如下

期望每次提交 得到的值 是不同的，谢谢大佬们

Answer 1

问题是你的第一个循环出问题了
this.tableData.forEach(sub => {

sampleProcessList = sub.sampleProcessInfo.sampleProcessList

})
这个不是把tableData中所有元素的sub.sampleProcessInfo.sampleProcessList是对象，你需要赋值给sampleProcessList，你现在的处理逻辑是循环过程中，是每个都会重新赋值一次，直到循环结束，你sampleProcessList拿到数据其实就是tableData的最后一个元素的数据，如果所有的sub.sampleProcessInfo.sampleProcessList是对象，你需要sampleProcessList.push(sub.sampleProcessInfo.sampleProcessList),如果是数组，sampleProcessList=sampleProcessList.concat(sub.sampleProcessInfo.sampleProcessList)

Answer 2

this.tableData.forEach(sub => {
  sampleProcessList = sub.sampleProcessInfo.sampleProcessList
})

等价于

sampleProcessList = this.tableData[this.tableData.length - 1]?.sampleProcessInfo.sampleProcessList

---

let sampleProcessListss = JSON.parse(JSON.stringify(sampleProcessList))
  sampleProcessListss.find(element => {
    if (element.id === this.input.selectSampleProcess) {
      this.processName = element.processName
    }
  })

等价于

this.processName = sampleProcessList.find(v=>v.id === this.input.selectSampleProcess)?.processName

---

      const idList = this.ids.map(i => i)

      this.tableData.forEach(v => {
        if (idList.includes(v.id)) {
          v.processName = this.processName
        }
      })
      console.log(this.processName);
      }

等价于没写，毕竟没有 this.processName 赋值

---

最后就看前两句就行了，

// 获取表格中最后一行的 sampleProcessInfo.sampleProcessList
sampleProcessList = this.tableData[this.tableData.length - 1]?.sampleProcessInfo.sampleProcessList

// 从 sampleProcessList 找到和 selectSampleProcess 的第一条数据的 processName
this.processName = sampleProcessList.find(v=>v.id === this.input.selectSampleProcess)?.processName