Converting big strings of number into Number

#javascript

there are several ways used to convert a string to number such as

Number(str)
parseInt(str, 10)
(+str)
(str * 1) and so on.. where str is a number string like str = "123"

str = "123"
'123'
console.log(+str)
Output: 123

However, the above ways don't work when you have a very big string

let str = "6145390195186705543"
console.log(Number(str))
Output: 6145390195186705000

Here We get unexpected output, because we are dealing with a big string number.

Walk around:

BigInt values represent numeric values which are too large to be represented by the number primitive.

Using BigInt to convert a big string number

let str = "6145390195186705543"
console.log(BigInt(str))
6145390195186705543n

And here we get the expected output with n appended at the end
In case you want to do some mathematical operations on your output, yeah, it's possible e.g output + 1n

6145390195186705543n + 1n

6145390195186705544n

You can check how I used this to solve a problem on leetcode:
Question link: https://leetcode.com/problems/plus-one/

My Solution

var plusOne = function(digits) {
    let fin=[]
    let comb =singleValue(digits)
    comb = BigInt(comb)
    comb = comb +1n
    let arr = comb.toString().split('')
    for(let i=0; i<arr.length; i++){
        fin.push(Number(arr[i]))
    }
    return fin

};


 function singleValue(arr){
    let str = ""
    for(let i=0; i<arr.length; i++){
        str +=arr[i]
    }
    return str

}