Loop through an object of objects

Question

There is an object containing objects having this form:

bigObject: {
 "a - values": { atr: true}
 "a - items": { atr: true}
 "a - others": { atr: false}
 "b - values": { atr: true}
 "b - items": { atr: true}
 "b - others": { atr: false}
 "c - values": { atr: false}
 "c - items": { atr: true}
 "c - others": { atr: false}
}

I use this object inside a function to check every time one of the attributes had changed its boolean value: onButtonClicked(item)

it does something like:

onButtonClicked(item) {
 bigObject[item.id].atr= !bigObject[item.id].atr;
}

Inside this function, I want to split them in order to be able to check the values for objects starting with a, b and c separately. For that I did: const toCheck = item.id.split("-")[0];

this works fine, it will take only the objects starting with a if that one was clicked.

the next step is to check if there are both true and false attributes for a specific letter.

For this I tried to do it like:

let countFalse = 0;
let countTrue = 0;
 bigObject.forEach(x => {
 if ((x.split("-")[0]) === toCheck) {
 if (x.atr) {
 countTrue++;
 } else countFalse++;
 }
 if (countTrue && countFalse) {
 console.log("has both true and false attributes");
 } else console.log("nope");
 });

So I'm splitting the original name to get rid of (values, items, others) and after that I try to count the true and false attributes. If there are both of them, show a message telling that otherwise, no.

Something is wrong but I don't understand what. Any ideas?

• Nina Scholz: where do you get forEach from?
• Leo Messi: @NinaScholz modified it
• MattG: Shouldn't the final if statement be outside the loop. What output are you getting?
• Leo Messi: the error I get is bigObject.forEach is not a function
• charlietfl: You get that error because forEach is for arrays not object literals

Answer 1

You could iterate the entries with splitting by ' - ' instead of '-'.

var bigObject = { "a - values": { atr: true }, "a - items": { atr: true }, "a - others": { atr: false }, "b - values": { atr: true }, "b - items": { atr: true }, "b - others": { atr: false }, "c - values": { atr: false }, "c - items": { atr: true }, "c - others": { atr: false } },
 countFalse = 0,
 countTrue = 0,
 toCheck = 'a';
Object.entries(bigObject).forEach(([k, v]) => {
 if (k.split(" - ")[0] !== toCheck) {
 return;
 }
 if (v.atr) {
 countTrue++;
 } else {
 countFalse++;
 }
});
if (countTrue && countFalse) {
 console.log("has both true and false attributes");
} else {
 console.log("nope");
}

A more compact version with an object for counting.

var object = { "a - values": { atr: true }, "a - items": { atr: true }, "a - others": { atr: false }, "b - values": { atr: true }, "b - items": { atr: true }, "b - others": { atr: false }, "c - values": { atr: false }, "c - items": { atr: true }, "c - others": { atr: false } },
 count = { false: 0, true: 0 },
 toCheck = 'a';
Object.entries(object).forEach(([k, { atr }]) => count[atr] += k.startsWith(toCheck));
if (count.true && count.false) {
 console.log("has both true and false attributes");
} else {
 console.log("nope");
}
console.log(count);

• Nina Scholz: @VigneshRaja, arrow functions are not supported as well, but op is using it, beside let. => ES6
• Leo Messi: The first version doesn't work for me. countTrue and countFalse are 0 all the time. but the second one is good.

Answer 2

As I know, forEach does not iterate over objects. I suggest you use

const bigObjectKeys = Object.keys(bigObject)

than iterate like this:

bigObjectKeys.forEach(element => { bigObject[element] ...})

Or use lodash forEach, it can iterate over objects.

https://lodash.com/docs/4.17.10#forEach

Answer 3

Things you got wrong and to be fixed :

1. Iterate through the keys/entries of an object.
2. Split with -, not with -.
3. Check using if, only after you have completed iterating through all elements.

var countFalse = 0;
var countTrue = 0;
var bigObject= {
 "a - values": { atr: true},
 "a - items": { atr: true},
 "a - others": { atr: false},
 "b - values": { atr: true},
 "b - items": { atr: true},
 "b - others": { atr: false},
 "c - values": { atr: false},
 "c - items": { atr: true},
 "c - others": { atr: false}
}
var toCheck = "a";
 Object.keys(bigObject).forEach(x => {
 if ((x.split(" - ")[0]) === toCheck) {
 if (bigObject[x].atr) {
 countTrue++;
 } else countFalse++;
 }
 });
 
 if (countTrue && countFalse) {
 console.log("has both true and false attributes");
 } else console.log("nope");

To be more efficient,

var countFalse = 0, countTrue = 0;
var bigObject= {
 "a - values": { atr: true},
 "a - items": { atr: false},
 "a - others": { atr: false},
 "b - values": { atr: true},
 "b - items": { atr: true},
 "b - others": { atr: false},
 "c - values": { atr: false},
 "c - items": { atr: true},
 "c - others": { atr: false}
}
var toCheck = "a";
Object.keys(bigObject).forEach(x => {
 if ((x.split(" - ")[0] === toCheck) && !(countTrue>0 && countFalse>0))
 {
 bigObject[x].atr ? countTrue++ : countFalse++;
 }
});
if (countTrue && countFalse) {
 console.log("has both true and false attributes");
 } else console.log("nope");

Answer 4

Could use Array#filter and Array#every on the Object entries

const isMatching = (str) =>{
 const arr = Object.entries(bigObject).filter(e=> e[0].startsWith(str));
 // makes sure every entry has same `atr` as the first entry 
 return arr.every(e => e[1].atr === arr[0][1].atr);
}
['a','b','c'].forEach(s => console.log(s, isMatching(s)))

<script>
const bigObject= {
 "a - values": { atr: true},
 "a - items": { atr: true},
 "a - others": { atr: false},
 "b - values": { atr: true},
 "b - items": { atr: true},
 "b - others": { atr: false},
 "c - values": { atr: false},
 "c - items": { atr: false},
 "c - others": { atr: false}
}
</script>