Javascript - Set all values in nested object to null

Question

I have the following object, and want to set all the values in it to null, while maintaining the objects structure

var objs = {
    a: {
        prop1: {id: null, val: 10},
        prop2: true,
        prop3: null,
    },
    b: {
        prop1: {id: null, val: 20},
        prop2: true,
        prop3: null,
    },
    c: 10
}

The results needs to be:

var objs = {
    a: {
        prop1: {id: null, val: null},
        prop2: null,
        prop3: null,
    },
    b: {
        prop1: {id: null, val: null},
        prop2: null,
        prop3: null,
    },
    c: null
}

This solution works for me, and I believe it should work for any depth. But if there is more elegant or efficient solution, please let me know.

var objs = {
    a: {
        prop1: {id: null, val: 10},
        prop2: true,
        prop3: null,
    },
    b: {
        prop1: {id: null, val: 20},
        prop2: true,
        prop3: null,
    },
    c: 10
}

function nullTest(val){
    for (key in val) {
        if(typeof(val[key]) !== 'object') {
            val[key] = null;
        } else {
            val[key] = nullTest(val[key])
        }
    }
    return val
}

console.log(nullTest(objs));

Thanks

Answer 1

You can use Object.keys to get all the keys of the object, loop over them using forEach, and recurse accordingly.

var objs = {
    a: {
        prop1: {id: null, val: 10},
        prop2: true,
        prop3: null,
    },
    b: {
        prop1: {id: null, val: 20},
        prop2: true,
        prop3: null,
    },
    c: 10
}
function nullTest(val){
    return Object.keys(val).forEach(k=>val[k]=val[k]===Object(val[k])?nullTest(val[k]):null), val;
}
console.log(nullTest(objs));

You can use Array.prototype.reduce to create a new object without modifying the old one.

const objs = {
    a: {
        prop1: {id: null, val: 10},
        prop2: true,
        prop3: null,
    },
    b: {
        prop1: {id: null, val: 20},
        prop2: true,
        prop3: null,
    },
    c: 10
};
function nullTest(val){
    return Object.keys(val).reduce((acc,key)=>(acc[key]=val[key]===Object(val[key])?nullTest(val[key]):null,acc),{});
}
console.log('new object:', nullTest(objs));
console.log('objs:', objs);