Create nice looking array object based on key value in a for loop

I’m having a little bit of trouble creating an object of a couple of fields, pushing them and creating a nice looking object:

// function to extract integer from key field...
function pad3(position) {
    return parseInt((position < 10 ? position.charAt(1) : position))
}

for (let field of formData) {
        key = field[0]
        val = field[1]
        position = pad3(key.substring(0,2)) // 00- becomes 0, 01- becomes 1 etc...

        let obj = []
        obj = {[key.substring(3,key.length)]: val}
        arr.push(obj)   
}

Console logging key and val within this loop during iteration looks like:

console.log(key) // 00-account_a
console.log(val) // 111
console.log(key) // 00-account_b
console.log(val) // 222

console.log(key) // 01-account_a
console.log(val) // 333
console.log(key) // 01-account_b
console.log(val) // 444

console.log(key) // 02-account_a
console.log(val) // 555
console.log(key) // 02-account_b
console.log(val) // 666

and so on …

I would like to create a nice looking Array object from this data but I’m struggling…
How do I create a nice looking array object based on the position variable?

Something Like:

Accounts [
[0] {   // <-- [0] based on "position" variable ...
    account_a: 111,
    account_b:222
},
[1] { 
    account_a: 333,
    account_b:444
},
[2] { 
    account_a: 555,
    account_b:666
},
]