Javascript: key/value storage in object with multilevel nesting

Question

I have been given two arrays:-

var keys = ['a.b', 'a.c.d', 'a.e', 'h[0]'];
var values = [10, 20, {}, 40];

The output that I want is:-

{
    a: { 
         b: 10, 
         c: {
            d: 20
         }, 
         e: {}
    },
    h: [40]
}

What I have tried so far is

let constructObject = (keys, values) => {
    let output = {};
    for(let i = 0; i<keys.length; i++) {
        let props = keys[i].split('.');
        for(let j=0; j<props.length;j++) {
            if(props.length > (j+ 1)) {
                if(output[props[j]] == undefined) {
                  output[props[j]] = {};
                }
            } else {
              output[props[j]] = values[i];
            }
        }
    }
    return output;
}

The above code is not nesting deeper. I tried to store nested level key also using for loop but could not get any way to store keys, As javascript only gives way to store value not nested level keys.

Hi there. Can you let us know what approaches you have tried? Where exactly are you stuck? — JasperZelf
– JasperZelf, Commented Apr 24, 2020 at 6:44
Let us know what you have done please, so we can assist with an answer. — Ryan
– Ryan, Commented Apr 24, 2020 at 6:49
@NinaScholz Please reopen the question. I have updated my question.. — Ayush Kumar
– Ayush Kumar, Commented Apr 24, 2020 at 7:07
I haven't found a dupe that also can handle arrays, but the dupe targets from this question has both: creating an object from strings/paths (w/o arrays) and settings properties (w/ arrays) -> Dynamically updating a JavaScript object from a string path — Andreas
– Andreas, Commented Apr 24, 2020 at 9:12

Nina Scholz · Accepted Answer · 2020-04-24 09:18:59Z

You could separate the pathes into smaller parts, like properties and indices and build new object by respecting the next key and decide if an array or an object has to be taken.

function setValue(target, keys, value) {
    const
        isWrapped = s => s.startsWith('[') && s.endsWith(']'),
        unwrap = s => isWrapped(s) ? s.slice(1, -1) : s,
        path = keys.match(/\[[^\]+]\]|[^\.\[\]]+/g),
        last = path.pop();

    path
        .reduce((o, k, i, { [i + 1]: next = last }) =>
            o[unwrap(k)] = o[unwrap(k)] || (isWrapped(next) ? [] : {}), target)
        [unwrap(last)] = value;
}

var keys = ['a.b', 'a.c.d', 'a.e', 'h[0]'],
    values = [10, 20, {}, 40],
    i,
    l = keys.length,
    result = {};

for (i = 0; i < l; i++) setValue(result, keys[i], values[i]);

console.log(result);

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

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