一种在不知道嵌套 js 对象中的路径的情况下访问属性的方法

问题描述：

有没有办法在不知道路径的情况下访问对象中的嵌套属性?例如我可以有这样的东西

is there a way to access a nested property within an object without knowing its path? For instance I could have something like this

let test1 = {
  location: {
    state: {
     className: 'myCalss'
    }
 }
};

let test2 = {
  params: {
    className: 'myCalss'
  }
};

有没有巧妙的方法来提取"className 属性?我有一个解决方案，但它很丑陋，它只考虑了这两种情况，我想知道是否有更灵活的方法可以做

Is there neat way to 'extract' className property? I have a solution but it's pretty ugly, and it accounts just for this two cases, I was wondering if there is something more flexible I could do

答

这是创建嵌套属性 getter 的一种优雅的方法:

Here's a somewhat elegant approach to creating nested property getters:

const getProperty = property => {
  const getter = o => {
    if (o && typeof o === 'object') {
      return Object.entries(o)
        .map(([key, value]) => key === property ? value : getter(value))
        .filter(Boolean)
        .shift()
    }
  }

  return getter
}

const test1 = {
  location: {
    state: {
      className: 'test1'
    }
  }
}

const test2 = {
  params: {
    className: 'test2'
  }
}

const test3 = {}

const getClassName = getProperty('className')

console.log(getClassName(test1))
console.log(getClassName(test2))
console.log(getClassName(test3))

如果你想防止循环对象导致堆栈溢出，我建议使用 WeakSet 来跟踪迭代对象引用:

If you want to prevent cyclical objects from causing a stack overflow, I suggest using a WeakSet to keep track of iterated object references:

const getProperty = property => {
  const getter = (o, ws = new WeakSet()) => {
    if (o && typeof o === 'object' && !ws.has(o)) {
      ws.add(o)
      return Object.entries(o)
        .map(([key, value]) => key === property ? value : getter(value, ws))
        .filter(Boolean)
        .shift()
    }
  }

  return getter
}

const test1 = {
  location: {
    state: {
      className: 'test1'
    }
  }
}

const test2 = {
  params: {
    className: 'test2'
  }
}

const test3 = {}
const test4 = {
  a: {
    b: {}
  }
}

test4.a.self = test4
test4.a.b.self = test4
test4.a.b.className = 'test4'

const getClassName = getProperty('className')

console.log(getClassName(test1))
console.log(getClassName(test2))
console.log(getClassName(test3))
console.log(getClassName(test4))

一种在不知道嵌套 js 对象中的路径的情况下访问属性的方法

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