a problem while learning JavaScriptt

[lucid granite]

Hello , I took a course to learn JavaScript so im in the syntax , control flow & basic functions so ive done this lecture and I think I got 99% of all infromation thats according that I was develop a little of Lua. there is an practices to just learn this basics and practice so I had an headche with 2 questions and I need help to explain this 2 question and why we write this
// Q1 . Create a for loop that iterates from 0 to 10, but only prints even numbers to the console.

let array_length = numbers.length

for (let i = 0; i < array_length; i++) {
    let current_value = numbers[i]
    let is_even = current_value % 2 === 0
    if (is_even) {
        console.log(current_value)
    }
}```
`// Q2 . Given an array numbers, write a while loop that continues to sum the numbers until the sum is greater than 100, then exits the loop.`
```let array_numbers = [1, 2, 4, 5, 6, 10, 50, 70, 101]
let sum = 0
let i = 0

while (sum < 100) {
    let current_value = array_numbers[i]
    sum = sum + current_value
    i++
    console.log(sum)
}```

[livid hazel]

Lua is a completely different language. Were you learning Javascipt or Lua?

If you understood 99% and can't understand this code, either you were studying Lua or they didn't cover these topics.

[lucid granite]

I'm talking that I understand the syntax of JavaScript , control flow and basics easly cause it's simillar of lua in this side .. I understand 60% of this 2 questions but im searching on understanding it fully

[livid hazel]

OK. Specify which parts you don't understand.

[lucid granite]

Q1 I understand it after looking a while at it but question2
why we are putting let sum = 0 and let i = 0
and why when we run it this is the log appear? and what does the i++ doing here specifically i know its an short of i = i+1 but what its job here in this code

[livid hazel]

Javascript does not automatically initialize variables with a value. As a consequence, both sum and i have a value of undefined if you don't assign to 0. This is problematic, because adding any number to undefined results in NaN.

The i++ increments i by 1.

[lucid granite]

increase for what specifically in this code ?

[livid hazel]

The i is being used as the index of the array. It is incremented to go to the next array element.

[livid hazel]

I just answered that while you were asking.

[lucid granite]

okay

[lucid granite]

so i have to give them a value if i dont then it will be NaN

[livid hazel]

/run

let num;
num++;
console.log(num);

[viscid marten]

Here is your js(18.15.0) output @livid hazel

NaN

[livid hazel]

/run

let num = 0;
num++;
console.log(num);

[viscid marten]

Here is your js(18.15.0) output @livid hazel

1

[lucid granite]

okay okay I got it , I have another question for you now im new on programming .. the way of become an expert on JavaScript or any other language is just to code and repeat and i will be expert by the time ? and is it okay to feel like untrusting ?

untrusting that I didn't got the point even if i got it

[livid hazel]

Writing code is the only way to get good at writing code.

It is normal to have uncertainties in the beginning. It is actually healthier to have uncertanties. There are some beginners who are very confident in their incorrect beliefs. This prevents them from learning, because you have to realize that you don't know something before you can learn it.