How can I loop through an array

Question

I'm having problems with looping through an array. I'm making an RPG bot for Discord, and I need to display the inventory of the player when prompted. I've tried to use Object.values(), Object.map() and Object.entries(). The names of the items are already worked out with Object.keys(inventory), but the values are the problem.

var invItems = Object.keys(inventory);
var InvValues = Object.entries(inventory);
for (var i = 0; i <= invItems.length; i += 1) {
       if (invValues[i[1]] > 0) {
           message.channel.send(`${invValues[i[1]]}x ${invItems[i]}`);
       }
};

I'm a beginning coder, so please explain more detailed than you usually may do.

palaѕн · Accepted Answer · 2020-04-15 13:10:41Z

You can send values to message.channel directly using for...of loop like:

for (let [key, value] of Object.entries(inventory)) {
  if (value > 0) {
    message.channel.send(`${value}x ${key}`);
  }
}

Explanation:

The Object.entries() method returns an array of a given object's own enumerable string-keyed property [key, value] pairs. So, when we use it like:

const object1 = {
  a: 'somestring',
  b: 42
};

console.log(Object.entries(object1));

You can we get get an array back and each inside array is another array of key-value pair. Now, we can get each key & value using array destructuring and for...of loop like:

const object1 = {
  a: 'somestring',
  b: 42
};

for (let [key, value] of Object.entries(object1)) {
  console.log(`${key}: ${value}`);
}

// Returns:
// "a: somestring"
// "b: 42"

You can see this now returns all the keys and values properly. We have to just modify it a little bit to match your requirement and send the required message back.

turtlehacker · Accepted Answer · 2020-04-17 13:16:52Z

1

var invItems = Object.keys(inventory);
var invValues = Object.entries(inventory); // fixed the capital i

for (var i = 0; i <= invItems.length; i += 1) {

   if (invValues[i] > 0) {
       message.channel.send(`${invValues[i]}x ${invItems[i]}`);
   }
};

You are not using i as an index rather you are trying to access i[1] as if it were an array

also, in Javascript, you can also do a JSON.stringify to see the object structure. this will print your inventory to a JSON String.

//this may help you see what the inventory looks like
for(let i = 0; i<inventory.length; i+=1)
console.log(JSON.stringify(inventory[i]));

edited Apr 17, 2020 at 13:16

answered Apr 15, 2020 at 13:01

turtlehacker

439 bronze badges

Comments

Damon · Accepted Answer · 2020-04-15 13:08:24Z

0

You are on the right track with Object.entries which will provide an array of key/value pair arrays. Note that here: invValues[i[1]] you are trying to access a property 1 of i with is probably undefined. You can actually avoid some complication if you iterate with forEach here.

const inventory = {
  itemA: 'description for A',
  itemB: 'description for B'
}

Object.entries(inventory).forEach(([key, value]) => {
  // replace with message.channel.send(...)
  console.log(`${key}: ${value}`)
})

answered Apr 15, 2020 at 13:08

Damon

4,3562 gold badges19 silver badges27 bronze badges

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