Loop through object containing boolean values

Question

I have an object in key/value pairs that may contain boolean values. I need to evaluate the type of the value so I know what to return. So let's say I have an object that looks like:

{ 
 aKey: false,
 anotherKey: 4,
 yetAnotherKey: true
}

I want to loop through each key/value pair there and do something different depending on the type of the value. If I use Object.keys(options).map((key, index), it transforms the boolean values from true/false to 0/1, so I have no way of knowing that those are actually booleans.

What is the best way to go about this?

There shouldn’t be any transformation happening based on what you’ve pasted. If you use the builtin typeof function on the key you should be able to get what you need. — Antiokus, Aug 20 '18 at 23:08
Can't help but say, if you don't know in advance what keys to expect or what types they will have, then you are dealing with a huge mess, and the inevitable outcome is a huge mess with more of the same piled on top... — Peter B, Aug 20 '18 at 23:18

score 2 · Accepted Answer · answered Aug 20 '18 at 23:13

I think you just "oopsied" - you haven't even checked the value of the options object in your map function. The second parameter provided to an Array#map callback is always the index.

Extending your code to check the type of the value in options:

Object.keys(options).map((key, i, all_keys) => {
  let val = options[key];
  console.log(typeof val)
  ...
});

Consider reviewing the different methods of iteration / enumeration in JavaScript, e.g. https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Loops_and_iteration

How to iterate over a JavaScript object?

I still prefer to use the built-in functions, it's much cleaner than old school for loops in this case. — user1795832, Aug 20 '18 at 23:23

score 1 · Answer 2 · answered Aug 20 '18 at 23:15

Your .map(key, index) is looping over the array ["aKey", "anotherKey", "yetAnotherKey"] and losing the values in options. Maybe something like this would work for you:

for( o in options ){
    console.log(o, options[o])
}

> aKey false
> anotherKey 4
> yetAnotherKey true

Loop through object containing boolean values

2 Answers2