How to use an array of keys to fetch the value from a Javascript object

Question

If there is a Javascript object with multiple levels, as in:

myObject = {
        a: 12,
        obj11: {
                obj111: \'John\',
                b         


        

Answer 1

To increment the discussion, if you're using lodash you can also use the function _.get to get the value like this:

_.get(myObject, ['obj111', 'obj1111'])
//returns 'John'

If you object has properties with array values you can also get by indexes

var obj = {
        a: 1,
        b:[{
           d:4,
           c:8
        }]

_.get(obj, ['b','0','d'])
//returns 4

Source: https://lodash.com/docs/4.17.4#get

Answer 2

You could reduce the array with the keys and take an object as default value.

function getValue(object, path) {
    return path.reduce(function (r, k) {
        return (r || {})[k];
    }, object);
}

var object = { a: 12, obj11: { obj111: 'John', b: 13, obj1111: { a: 15, b: 35 }, obj21: { a: 15, b: 16 } } };

console.log(getValue(object, ['obj11', 'b']));
console.log(getValue(object, ['obj11', 'obj1111', 'a']));
console.log(getValue(object, ['obj11', 'obj21']));

.as-console-wrapper { max-height: 100% !important; top: 0; }

Answer 3

You can do this with a reduce() one-liner. Of course if you want to wrap it in a function, you can do that too.

var myObject = {
    a: 12,
   obj11: {
           obj111: 'John',
           b:13,
           obj1111: { a:15,
                      b: 35 }
           },
   obj21: {
           a:15,
           b:16 }
}

var arr =   ['obj11','b']
var val = arr.reduce((acc,curr) => acc[curr], myObject)
console.log(val)

var arr =   ['obj11','obj1111', 'b']
var val = arr.reduce((acc,curr) => acc[curr], myObject)
console.log(val)