CODEWITHSUNDEEP
javascriptarrays
user1354934
user1354934

Reputation: 8841

How to take an array, and insert commas between each item?

I am trying to understand how to take an array like [1,2,3,4,5] and then between each index, add a , so the array becomes [1, ', ', 2, ', ', 3, ', ', 4, ', ', 5]

I know it sounds stupid but I'm having some issues with it.

Basically, I want to use something like splice() method, so that I can iterate over the array and each odd index, I can do splice(index, 0, ', ').

Upvotes: 6

Views: 5949

Answers (7)

RomanPerekhrest
RomanPerekhrest

Reputation: 92854

Short solution using Array.prototype.join(), Array.prototype.map() and String.prototype.match() functions:

var arr = [1,2,3,4,5],
    newArr = arr.join(',').match(/\w+|\W+/g).map(function(v){
        return (isNaN(v))? v : +v;  // considering numeric values
    });

console.log(newArr);

You wanted splice approach? Here it is:

var arr = [1,2,3,4,5];
for (var i = 1; i < arr.length; i+=2) {
    arr.splice(i, 0, ',');
}

console.log(arr);

Upvotes: 1

Paweł
Paweł

Reputation: 4516

With just two methods:

Edit

If you want to save your commas use some regexp instead:

var c = a.join(', , , ').split(/\s(?=,\s)/);

var a = [1,2,3,4,5];
var b = a.join(' , ').split(' ');
var c = a.join(', ,  , ').split(/\s(?=,\s)/);
console.log(b,c);

Upvotes: 1

guest271314
guest271314

Reputation: 1

You can use a variable at .splice() to increment index by 2

var arr = [1,2,3,4,5];
for (let i = 1, len = arr.length * 2; arr.length < len - 1; arr.splice(i, 0, ","), i += 2);
console.log(arr);

Upvotes: 0

Sangharsh
Sangharsh

Reputation: 3019

Use .reduce()

  1. Start with empty array
  2. Push an element of array then push ', '
  3. At last remove last ', ' using .pop()

var array1 = [1, 2, 3, 4, 5]

var array2 = array1.reduce(function(acc, val) {
  acc.push(val);
  acc.push(', ');
  return acc;
}, []);

array2.pop();

console.log(array2);

Upvotes: 3

rasmeister
rasmeister

Reputation: 1996

console.log([1,2,3,4,5].reduce(function(acc, val, idx, list) {
  acc.push(val);
  if (idx < list.length - 1) {
    acc.push(',');

  }
  return acc;
}, []));

Upvotes: 1

Mihai Alexandru-Ionut
Mihai Alexandru-Ionut

Reputation: 48357

You can use .reduce method which accepts as parameter a callback function.

The reduce() method applies a function against an accumulator and each value of the array (from left-to-right) to reduce it to a single value.

var array=[1,2,3,4,5];
console.log(array.reduce(function(a,b){
    return a.concat(b).concat(",");
},[]).slice(0,-1));

Upvotes: 5

SimpleJ
SimpleJ

Reputation: 14768

You can use reduce to create a new array with the inserted values:

function weaveArray(array, weaveValue) {
  const {length} = array;
  return array.reduce((result, value, i) => {
    if(i < length - 1) {
      result.push(value, weaveValue);
    } else {
      result.push(value);
    }
    return result;
  }, []);
}

console.log(
  weaveArray([1,2,3,4,5], ",")
);

Upvotes: 2

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