How To Get An Array From Splitted String That Has Negative Value

Question

I don't know what is the right question for this.

I want to make this number -800 become [-8,0,0] is anyone can build it

The first thing that I do, is to make the number become a string and using the map function I iterate it becomes an array like this

const number = -800;
const numberString = number.toString();
const arrayString = numberString.split``.map((x) => +x);

console.log(arrayString)

But the result is [ NaN, 8, 0, 0 ]

How to change the NaN and first index 8 become -8 without disturbing the other index. So it becomes [-8, 0, 0]

Is anybody can help me?

Thanks.

I recommend accepting Hao Wu's answer, it'll be more performant than mine I believe — Nick
– Nick, Commented Jan 4, 2021 at 1:49
Thanks Nick, i think you both give the great answer. But yesterday you commenting first, so i use your answer. Well, i will change it. Thanks — theDreamer911
– theDreamer911, Commented Jan 5, 2021 at 5:13

Hao Wu · Accepted Answer · 2021-01-04 01:46:33Z

4

Try numberString.match(/-?\d/g) instead of split

const number = -800;
const numberString = number.toString();
const arrayString = numberString.match(/-?\d/g).map(x => +x);

console.log(arrayString)

answered Jan 4, 2021 at 1:46

Hao Wu

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2 Comments

Nick Over a year ago

Oh, this is better than mine

CodeDead Over a year ago

@Nick They are about equal when it comes to the performance: jsfiddle.net/9evxz6rj/1 vs jsfiddle.net/9evxz6rj/0

Nick · Accepted Answer · 2021-01-04 01:45:48Z

3

One possible solution is to just do this operation on the absolute value and, during the map, check if the number was negative (only for the first index).

const number = -800;
const numberString = Math.abs(number).toString();
const arrayString = numberString.split``.map((x, i) => i == 0 && number < 0 ? -x : +x);

console.log(arrayString)

answered Jan 4, 2021 at 1:45

Nick

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Comments

Nguyễn Văn Phong · Accepted Answer · 2021-01-04 01:53:00Z

1

If you're not clear about Regex, you can use Array.from to convert a string to an array number. Then handle the first number based on the sign of original number.

console.log(convertNumberToArray(800));
console.log(convertNumberToArray(-800));

function convertNumberToArray(number){
  var result = Array.from(Math.abs(number).toString(), Number);
  result[0] *= number <= 0 ? -1 : 1;
  return result;
}

answered Jan 4, 2021 at 1:53

Nguyễn Văn Phong

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Comments

Binh Vo · Accepted Answer · 2021-01-04 01:55:38Z

1

Use String#match with regex which matches optional - with the dig it.

var number = -800;
var numberString = number.toString().match(/-?\d/g);
var numberInt = [];

for (var i = 0; i < numberString.length; i++) {
    numberInt.push(parseInt(numberString[i]));
}
console.log(numberInt);

answered Jan 4, 2021 at 1:55

Binh Vo

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