Question

我试图用另一个看似微不足道的对象来更新JS对象，但该值未更新。

MIN(ID_CMP)

似乎SELECT只是一些浮动的东西，在我试图更新其值时与ORDER BY无关。但是，我不知道如何进行更新或丢失了什么。

编辑：预期的结果是一旦找到let sampleObj = { id: 1, name: 'Kelly' } let userData = [{ students: [{ id: 1, name: 'Sandra' }] }, { students: [{ id: 2, name: 'Jerome' }] } ] for (let group of userData) { for (let student of group.students) { if (student.id === sampleObj.id) { console.log('updating student object') student = sampleObj // student = { ...sampleObj } (another failed attempt) // userData[group].students[student] = sampleObj (another failed attempt) } } } console.log('userData', userData)对象，就将student替换为userData。

Answer 1

请改用forEach(el, index)，以便您有可用的索引来进行更新：

let sampleObj = {
  id: 1,
  name: 'Kelly'
}

let userData = [{
    students: [{
      id: 1,
      name: 'Sandra'
    }]
  },
  {
    students: [{
      id: 2,
      name: 'Jerome'
    }]
  }
]

userData.forEach((group, m) => {
  group.students.forEach((student, n) => {
    if (student.id === sampleObj.id) {
      console.log('updating student object')
      userData[m].students[n] = sampleObj
    }
  })
})

console.log('userData', userData)

Answer 2

替换阵列项目不起作用。相反，您可以像这样替换学生对象的属性

for (let group of userData) {
  for (let student of group.students) {
    if (student.id === sampleObj.id) {
      console.log('updating student object')
      student = Object.assign(student, sampleObj);
    }
  }
}

它将把samplObj的所有属性分配给学生对象。

Answer 3

您永远不会更新实际的userData。要对其进行更新，应在循环中引用userData对象，而不是用于迭代该对象的临时变量。

因此，请尝试以下操作：

let sampleObj = { id: 1, name: 'Kelly' }

let userData = [
    {
    students: [
        { id: 1, name: 'Sandra' }
    ]
  },
  {
    students: [
        { id: 2, name: 'Jerome' }
    ]
  }
]
let j=0
for ( let group of userData ) {let i=0
    for ( let student of group.students ) { 
    if ( student.id === sampleObj.id ) {
        console.log('updating student object')
        userData[j].students[i] = sampleObj

      // student = { ...sampleObj }     (another failed attempt)
      // userData[group].students[student] = sampleObj     (another failed attempt)
    } i++;
  } j++;
}

console.log('userData', userData)

更新for循环内的Javascript对象属性

3 个答案: