[javascript] How can I convert a comma-separated string to an array?

I have a comma-separated string that I want to convert into an array, so I can loop through it.

Is there anything built-in to do this?

For example, I have this string

var str = "January,February,March,April,May,June,July,August,September,October,November,December";

Now I want to split this by the comma, and then store it in an array.

Hmm, split is dangerous IMHO as a string can always contain a comma. Observe the following:

var myArr = "a,b,c,d,e,f,g,','";
result = myArr.split(',');

So how would you interpret that? And what do you want the result to be? An array with:

['a', 'b', 'c', 'd', 'e', 'f', 'g', '\'', '\''] or
['a', 'b', 'c', 'd', 'e', 'f', 'g', ',']

Even if you escape the comma, you'd have a problem.

I quickly fiddled this together:

(function($) {
    $.extend({
        splitAttrString: function(theStr) {
            var attrs = [];

            var RefString = function(s) {
                this.value = s;
            };
            RefString.prototype.toString = function() {
                return this.value;
            };
            RefString.prototype.charAt = String.prototype.charAt;
            var data = new RefString(theStr);

            var getBlock = function(endChr, restString) {
                var block = '';
                var currChr = '';
                while ((currChr != endChr) && (restString.value !== '')) {
                    if (/'|"/.test(currChr)) {
                        block = $.trim(block) + getBlock(currChr, restString);
                    }
                    else if (/\{/.test(currChr)) {
                        block = $.trim(block) + getBlock('}', restString);
                    }
                    else if (/\[/.test(currChr)) {
                        block = $.trim(block) + getBlock(']', restString);
                    }
                    else {
                        block += currChr;
                    }
                    currChr = restString.charAt(0);
                    restString.value = restString.value.slice(1);
                }
                return $.trim(block);
            };

            do {
                var attr = getBlock(',', data);
                attrs.push(attr);
            }
            while (data.value !== '')
                ;
            return attrs;
        }
    });
})(jQuery);

A good solution for that:

let obj = ['A','B','C']

obj.map((c) => { return c. }).join(', ')

For an array of strings to a comma-separated string:

let months = ["January","Feb"];
let monthsString = months.join(", ");

The split() method is used to split a string into an array of substrings, and returns the new array.

var array = string.split(',');

Here is a function that will convert a string to an array, even if there is only one item in the list (no separator character):

function listToAray(fullString, separator) {
  var fullArray = [];

  if (fullString !== undefined) {
    if (fullString.indexOf(separator) == -1) {
      fullAray.push(fullString);
    } else {
      fullArray = fullString.split(separator);
    }
  }

  return fullArray;
}

Use it like this:

var myString = 'alpha,bravo,charlie,delta';
var myArray = listToArray(myString, ',');
myArray[2]; // charlie

var yourString = 'echo';
var yourArray = listToArray(yourString, ',');
yourArray[0]; // echo

I created this function because split throws out an error if there isn't any separator character in the string (only one item).

Pass your comma-separated string into this function and it will return an array, and if a comma-separated string is not found then it will return null.

function splitTheString(CommaSepStr) {
    var ResultArray = null;

    // Check if the string is null or so.
    if (CommaSepStr!= null) {

        var SplitChars = ',';

        // Check if the string has comma of not will go to else
        if (CommaSepStr.indexOf(SplitChars) >= 0) {
            ResultArray = CommaSepStr.split(SplitChars);

        }
        else {

            // The string has only one value, and we can also check
            // the length of the string or time and cross-check too.
            ResultArray = [CommaSepStr];
        }
    }
    return ResultArray;
}

As @oportocala mentions, an empty string will not result in the expected empty array.

So to counter, do:

str
.split(',')
.map(entry => entry.trim())
.filter(entry => entry)

For an array of expected integers, do:

str
.split(',')
.map(entry => parseInt(entry))
.filter(entry => typeof entry ==='number')

You can try the following snippet:

 var str = "How,are,you,doing,today?";
    var res = str.split(",");
    console.log("My Result:", res)

Watch out if you are aiming at integers, like 1,2,3,4,5. If you intend to use the elements of your array as integers and not as strings after splitting the string, consider converting them into such.

var str = "1,2,3,4,5,6";
var temp = new Array();
// This will return an array with strings "1", "2", etc.
temp = str.split(",");

Adding a loop like this,

for (a in temp ) {
    temp[a] = parseInt(temp[a], 10); // Explicitly include base as per Álvaro's comment
}

will return an array containing integers, and not strings.

Return function

var array = (new Function("return [" + str+ "];")());

Its accept string and objectstrings:

var string = "0,1";

var objectstring = '{Name:"Tshirt", CatGroupName:"Clothes", Gender:"male-female"}, {Name:"Dress", CatGroupName:"Clothes", Gender:"female"}, {Name:"Belt", CatGroupName:"Leather", Gender:"child"}';

var stringArray = (new Function("return [" + string+ "];")());

var objectStringArray = (new Function("return [" + objectstring+ "];")());

JSFiddle https://jsfiddle.net/7ne9L4Lj/1/

Note that the following:

var a = "";
var x = new Array();
x = a.split(",");
alert(x.length);

will alert 1

I had a similar issue, but more complex as I needed to transform a CSV file into an array of arrays (each line is one array element that inside has an array of items split by comma).

The easiest solution (and more secure I bet) was to use PapaParse which has a "no-header" option that transform the CSV file into an array of arrays, plus, it automatically detected the "," as my delimiter.

Plus, it is registered in Bower, so I only had to:

bower install papa-parse --save

And then use it in my code as follows:

var arrayOfArrays = Papa.parse(csvStringWithEnters), {header:false}).data;

I really liked it.

let str = "January,February,March,April,May,June,July,August,September,October,November,December"

let arr = str.split(',');

it will result:

["January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"]

and if you want to convert following to:

["January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"]

this:

"January,February,March,April,May,June,July,August,September,October,November,December";

use:

str = arr.join(',')

Shortest

str.split`,`

var str = "January,February,March,April,May,June,July,August,September,October,November,December";_x000D_
_x000D_
let arr = str.split`,`;_x000D_
_x000D_
console.log(arr);