Break array in smaller arrays that are split by spaces

Question

I have a string ' 1 22 333 4444 5 6 ', and I want ot make an array like this - [[1, 22], [22, 333], [4444, 5], [5, 6]];

I tried to use for... loop but it didn't help.

let str = ' 1 22 333 4444 5 6 ';
let arr = [];
for(let i = 0; i < str.length; i++)
 arr.push(str.slice(str.indexOf(' ', i),str.indexOf(' ',i+1)));

And it gave this output:

[ ' 1', '', ' 22', '', ' 333', '', ' 4444', '', ' 5', '', ' 6', '', '' ]

Instead of: [[1, 22], [22, 333], [4444, 5], [5, 6]];

Why is it wrong? Does anybody know how to do it?

• Joseph: Do you really want that last array to have [5, 6] or just [6] since the original string only had one 5 in it?
• brk: Whty not [333,4444]
• itdoesntwork: using regex would be smooth.

Answer 1

Based on the question, the format of the output is not clear. You can do it in few ways depending on the desired format of the output:

1) if you want every last item to be the first item of the next chunk

const input = ' 1 22 333 4444 5 6 ';
const result = input.trim().split(' ').map(Number).reduce((all, n, i, arr) => i ? [...all,[arr[i-1],n]] : [] ,[])
console.log(result);

2) if you want to split it in chunks of two

const input = ' 1 22 333 4444 5 6 ';
const result2 = input.match(/(\d+ \d+)/gi).map(a => a.split(' ').map(Number));
console.log(result2);

Answer 2

const res = ' 1 22 333 4444 5 6 '
 .split(' ')
 .filter(Boolean)
 .map(v => [v])
 .reduce((acc, curr, idx) => {
 acc = idx % 2 ? [...acc.slice(0, acc.length-1), acc[acc.length-1].concat(curr)] : [...acc, curr];
 return acc;
 }, []);
 
console.log(res);

Answer 3

It is not possible to do what you would like to do because the delimiter between each of the numbers is consistent for the entire string. You need to have one delimiter for each of the numbers, then a different delimiter for the groups.

For example;

let str = '1 22,333 4444,5 6';
let groups = str.split(",");
let arr = [];
for (let i = 0; i < groups.length; i++)
 arr.push(groups[i].split(" "));
 
console.log(arr);

• mscdeveloper: result arrays not integer values
• Adam Chubbuck: @NickA Perhaps that was an overly broad claim, but I try not to assume that the original poster wanted this in groups of two explicitly as one could reasonably assume that the groups of two were coincidental.
• Nick is tired: @AdamChubbuck I didn't notice something in the comments, just ignore me :)
• Nick is tired: @AdamChubbuck Although it's likely safe to assume that the groups of 2 are not coincidental due to: str.slice(str.indexOf(' ', **i**), str.indexOf(' ',**i+1**))
• Adam Chubbuck: @NickA Perhaps the OP can clarify.

Answer 4

As an alternative you could use a regex with a capturing group and positive lookahead to assert what follows are one or more digits and capture that in the second capturing group.

(\d+) (?=(\d+))

Then add group 1 and group 2 in an array to arr.

const regex = /(\d+) (?=(\d+))/g;
let m;
let str = ' 1 22 333 4444 5 6 ';
let arr = [];
while ((m = regex.exec(str)) !== null) {
 arr.push([m[1], m[2]]);
}
console.log(arr);

Answer 5

Maybe like this:

let str = ' 1 22 333 4444 5 6 ';
let arr = [];
let str_arr=str.split(' ');
for(let key in str_arr){
 if(str_arr[key]!=''){
 	 let add_arr=[];
 	 add_arr.push(parseInt(str_arr[key],10));
 	 let next_key=parseInt(key,10)+1;
 	 if(str_arr[next_key]){
 	 	add_arr.push(parseInt(str_arr[next_key],10));
 	 arr.push(add_arr);
 	 }
 }
}
console.log(arr);

Answer 6

You should run this code

let str = ' 1 22 333 4444 5 6 ';
let arr = [];
var res = str.split(" ");
console.log(res);
var a = res.filter(i => i !== "");
console.log(a);
var tempArr = [];
var counter = 0;
for (var i = 0; i < a.length; i++){
 counter++;
 tempArr.push(a[i]);
 if(counter == 2){
 arr.push(tempArr);
 tempArr = [];
 counter = 0;
 }
}
console.log(arr);

Answer 7

If I interpret the task right, this is one way you can solve it:

' 1 22 333 4444 5 6 '
 .trim()
 .split(' ')
 .reduce((arr, item, index) => {
 if (index % 2 === 0) {
 arr.push([ item ]);
 } else {
 arr.slice(-1)[0].push(item);
 }
 return arr;
 }, [])

Answer 8

let str = ' 1 22 333 4444 5 6 ';
let arr = [];
let temp = str.trim().split(" ");
for (let i = 0; i < temp.length - 1; i++)
 arr.push([parseInt(temp[i]), parseInt(temp[i + 1])]);
console.log(arr);
for (let i = 0; i < arr.length - 1; i++) {
 console.log(arr[i]);
}

the output of above code is

[[1, 22], [22, 333], [4444, 5], [5, 6]]
[1, 22] 
[22, 333]
[4444, 5]
[5, 6]

• Nick is tired: "the output of above code is" ... No it's not, you dropped [333, 4444]