calculate JSON.stringify(obj) to sum value of string? [duplicate]

Question

In my local storage I have some score value stored in array

var obj = localStorage.getItem("scoreList")

output

[0,10,10,0,10]

I want sum of this value like and return to data value

sum = 30

I have tried to convert into string value

var string = JSON.stringify(obj);
output "[0,10,10,0,10]"

How can I execute this sum value ?

Answer 1

localStorage.getItem("scoreList").replace(/(\[|\])/g, '').split(",").map(x => parseFloat(x)).reduce((a,b) => a+b, 0)

a simple way:

JSON.parse(localStorage.getItem("scoreList")).reduce((x, y) => x + y)

Answer 2

[0,10,10,0,10].reduce((sum, a) => sum + a, 0);

Answer 3

If you set the scoreList value as an array, that is:

localStorage.setItem('scoreList', [0,10,10,0,10])

When you get it back it will still be a string, so there's no need for any other kind of validation or data type transformation as you did with JSON.stringfy. The following shoud be enough:

const obj = localStorage.getItem("scoreList")
const total = obj.reduce((sum, item) => sum + item, 0);
//total = 30