if i already know an object`s structure,how can i eval the right value to the object?(javascript)

Question

If I have an Object like this:

let obj = {
  a:{
    b:{
      c:{
        d:{
         e:'nonono'
       }
     }
   }
 }
}

and I know the structure of the Object like that:

now I want to change the innermost layer of the Object, it is the "e" property. I want to assign another value to "e". I don't want like these ways below:

1. obj.a.b.c.d.e = 'another value';
2. var str1 = 'a.b.c.d.e'; obj[str1[0]][str[1]][str[2]][str[3]][str[4]];
3. var str1 = 'obj.a.b.c.d.e'; var str = str1 + "='another value'"; eval(str);

above these, I can change the property 'e' of the Object's Value, but I think it`s not grace to express what I mean.

If I have the Array like that: var arr= [a,b,c,d,e], I want to recursion a function to find the innermost layer Of the Object, but I try, if I reach the innermost layer of the Object, I lose the quote of the Object..... So I can't change the Object's Value that I want. I think I run these code, if you can help me to run.

let obj = {
  a: {
    b: {
      c: {
        d: {
          e: 'nonono'
        }
      }
    }
  }
}
let arr = ['a', 'b', 'c', 'd', 'e'];
let funKeepCite = (obj, index) => {
  if (obj[arr[index]]) {
    funKeepCite(obj[arr[index]], index + 1);
  } else {
    obj = 'test'
  }
}
funKeepCite(obj, 0)
console.log('the result', obj)

I can't change the value, I think I lose the quote of the Object, but the Answer of my question is use for .. in, and it can keep the quote of the Object, I am confused of these.

Answer 1

perhaps you want this kind

let obj = {
  a:{
    b:{
      c:{
        d:{
         e:'nonono'
       }
     }
   }
 }
}
function recurse(obj, val){
    for(var k in obj){
        if(typeof obj[k] == 'object') recurse(obj[k], val);
        else if(typeof obj[k] == 'string') obj[k] = val;
    }
}
recurse(obj, 'new');
console.log(obj);

Answer 2

You can't assign to obj which is just a local variable, you have to assign to a property. Recurse only until the second-to-last index, then use the last one for the assignment:

function funKeepCite(obj,index) {
  if (index < arr.length - 1) {
    funKeepCite(obj[arr[index]], index+1);
  } else if (index < arr.length) {
    obj[arr[index]] = 'test';
  } else
    throw new RangeError("there must be at least one property name in the array");
  }
}

Alternatively, use recursion with a return value and always assign:

function funKeepCite(obj, index) {
  if (index < arr.length) {
    obj[arr[index]] = funKeepCite(obj[arr[index]], index+1);
    return obj;
  } else {
    return 'test';
  }
}

Answer 3

I know this is not the best way to do it but as for your case, and "you already know the object's structure"

function setInnerObjVal will change the value of all the innermost object in obj.

let obj = {
  a: {
    b: {
      c: {
        d: {
          e: 'nonono'
        }
      }
    }
  }
  //try uncommenting the below codes
  /*,
  x: {
    y: {
      z: {
        val: 'maybe?'
      }
    }
  }*/
};

function setInnerObjVal(obj1, newVal, callback) {
  for (var i in obj1) {
    if (typeof obj1[i] == 'object') {
      setInnerObjVal(obj1[i], newVal, callback);
    } else {
      obj1[i] = newVal;
      if (typeof callback === 'function')
        callback();
      return;
    }
  }
}

//implement a callback to be called when the function is done.
//just in case your object is way way way deeper and you need to wait for the update to finish
var myCallback = function() {
  console.log(obj);
  //or do something else.
}

setInnerObjVal(obj, 'yesyesyes', myCallback);
//console.log(obj); //this will still log the oldvalue 'nonono' in case obj has a very deep object.

NOTE:

This function will change ALL objects under obj. (try uncommenting the values x,y,z,val)