Question

如果我想附加到一个现有的数组属性，最干净的解决方案是什么？

function adminConditional(user) {
    return {
      ...user,
      priority: 1,
      access: ['system2']
  }
}

console.log(
  {
    ...(adminConditional)({name: "andrew", type: "Admin"}), // function name can vary
    access: ['system1'] // always set
  }
)

// Expected output:
{
  access: ["system1", "system2"],
  name: "andrew",
  priority: 1,
  type: "Admin"
}
// Actual output:
{
  access: ["system1"],
  name: "andrew",
  priority: 1,
  type: "Admin"
}

相反，它用最后一个赋值覆盖了 access 的索引。

Answer 1

要使用扩展语法附加到数组，您可以使用以下语法：

let arr = [1,2,3];
let newArr = [...arr, 4];

newArr 将包含 [1,2,3,4]。同样可以应用于对象中，只需使用扩展运算符将属性引用到函数中即可获得相同的结果：

function adminConditional(user) {
    return {
      ...user,
      priority: 1,
      access: ['system2']
  }
}

console.log(
  {
    ...(adminConditional)({name: "andrew", type: "Admin"}),
    access: [...(adminConditional)({name: "andrew", type: "Admin"}).access, 'system1']
  }
)

Answer 2

您可能希望避免在 access 中重复，并避免两次调用该函数，因此没有捷径可走。我建议：

function adminConditional(user) {
    return {
      ...user,
      priority: 1,
      access: ['system2']
  }
}

let user = adminConditional({name: "andrew", type: "Admin"});
console.log(
  {
    ...user,
    access: [...new Set(['system1', ...user.access])]
  }
)

Answer 3

你可以简化逻辑

function adminConditional(user) {
  return {
    ...user,
    priority: 1,
    access: ['system2', ...user.access]
  };
}

console.log(
  {
    ...(adminConditional)({
      name: "andrew",
      type: "Admin",
      access: ['system1']
    })
  }
)

在对象中合并具有相同键的数组属性

3 个答案: