Javascript - how to valid variable chain

Question

I have in many places in my code the following format:

if (a && a.b && a.b.c && a.b.c.d) {
    //do something with a.b.c.d
}

Given a,b,c and d have a more complex names this is very ugly, time consuming and open places for mistakes.

Is there a "sugarcoating" for this, something like:

if (valid(a.b.c.d)) {
    //do something with a.b.c.d
}

Such functionality is not natively supported (even in ES6). But you can use libs, for example: https://lodash.com/docs#get — Jodi Supporter, Jan 25 '16 at 11:54

score 2 · Accepted Answer · answered Jan 25 '16 at 12:00

You can make recursive helper function to do this, for example:

function valid(obj, chain) {
    if (!chain.length) {
        return true;
    }
    var prop = chain.shift();
    return !obj.hasOwnProperty(prop) ? false : valid(obj[prop], chain);
}

var a = { b: { c: { d: 1 } } };

console.log(valid(a, ['b', 'c', 'd'])); // true
console.log(valid(a, ['b', 'c', 'e'])); // false

Javascript - how to valid variable chain

1 Answers1