JavaScript: Change All Values of Deeply nested object given path

Question

I have a JavaScript Object like this:

const Obj = {
  level1_1: "Value1",
  level1_2: "Value2",
  level1_3: "Value3",
  level1_4: "Value4",
  level1_5: {
    level2_1: {
      level3_1: { level4_1:1, level4_2:2, level4_3:3, level4_4:4 },
      level3_2: { level4_a:1, level4_b:2, level4_c:3, level4_d:4 } 
    },
    level2_2: {
      level3_1: { level4_5:1, level4_6:2, level4_7:3, level4_8:4 },
      level3_2: { level4_e:1, level4_f:2, level4_g:3, level4_h:4 } 
    }
  }
};

I want to change the values of all the keys inside level1_5.level2_1.Level3_1 object (ie. all level4) dynamically but not other values.

question from:https://stackoverflow.com/questions/65909406/javascript-change-all-values-of-deeply-nested-object-given-path

Answer 1

You can iterate over the object attributes recursively while keeping track of the remaining path properties, if reached the last one and it exists, you can then change all the values:

const Obj = {
  level1_1: "Value1",
  level1_2: "Value2",
  level1_3: "Value3",
  level1_4: "Value4",
  level1_5: {
    level2_1: {
      level3_1: { level4_1:1, level4_2:2, level4_3:3, level4_4:4 },
      level3_2: { level4_a:1, level4_b:2, level4_c:3, level4_d:4 } 
    },
    level2_2: {
      level3_1: { level4_5:1, level4_6:2, level4_7:3, level4_8:4 },
      level3_2: { level4_e:1, level4_f:2, level4_g:3, level4_h:4 } 
    }
  }
};

function getUpdatedObject (obj = {}, path = [], newVal) {
  const targetLevel = path.length;
  return (function setValuesOfPath (obj, path, newVal, currentLevel = 1) {
    if(currentLevel === targetLevel && path.length === 1) {
      const target = obj[path[0]];
      if(target) Object.keys(target).forEach(key => target[key] = newVal);
    }
    for (var property in obj) {
      if (obj.hasOwnProperty(property)) {
        if (typeof obj[property] === "object") {
          if(property === path[0]) path.shift();
          setValuesOfPath(obj[property], path, newVal, currentLevel+1);
        }
      }
    }
    return obj
  }(obj, path, newVal));
}

console.log(getUpdatedObject(Obj, ["level1_5", "level2_1", "level3_1"], "a"));