The Array.prototype.join() method:

var arr = ["Zero", "One", "Two"];

document.write(arr.join(", "));

Probably a bit late on the response for you BenColey but if anybody else finds this post who needs something similar, I've included an example Storyline file. In the example there are two Storyline variables unprocessedText and processedText. The input text field, sets the Storyline variable unprocessedText and the processed text, after being worked on via JavaScript is saved to the processedText variable, displayed in the text box labelled Output. There is a JavaScript function called processText which is initialised when the timeline starts on the slide. window.processText = function() { const player = GetPlayer(); // set the unprocessedText Storyline variable const unprocessedText = player.GetVar('unprocessedText'); // process the data let processedText = unprocessedText .split('\n') // Split by line breaks .map(line => line.trim()) // Trim whitespace from each line .filter(line => line) // Filter out any empty lines .join(', '); // Join with a comma and space // set the processedText Storyline variable player.SetVar('processedText',processedText); } The function is then called via the Process button "user clicks" trigger. window.processText();

...you get a better, more thorough explanation here: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/join

The method array.toString() actually calls array.join() which result in a string concatenated by commas. ref

var array = ['a','b','c','d','e','f'];
document.write(array.toString()); // "a,b,c,d,e,f"

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Also, you can implicitly call Array.toString() by making javascript coerce the Array to an string, like:

//will implicitly call array.toString()
str = ""+array;
str = `${array}`;

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Array.prototype.join()

The join() method joins all elements of an array into a string.

Arguments:

It accepts a separator as argument, but the default is already a comma ,

str = arr.join([separator = ','])

Examples:

var array = ['A', 'B', 'C'];
var myVar1 = array.join();      // 'A,B,C'
var myVar2 = array.join(', ');  // 'A, B, C'
var myVar3 = array.join(' + '); // 'A + B + C'
var myVar4 = array.join('');    // 'ABC'

Note:

If any element of the array is undefined or null , it is treated as an empty string.

Browser support:

It is available pretty much everywhere today, since IE 5.5 (1999~2000).

References

• ECMA Specification
• Mozilla
• MSDN

Array.prototype.join() is what you're looking for:

arr.join(',');

https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Array/join

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var arr = ['Hi', 'I', 'am', 'a', 'comma', 'separated', 'list'];

arr.join(',');  // === "Hi,I,am,a,comma,separated,list" 

const array = str.split(',');

MDN reference, mostly helpful for the possibly unexpected behavior of the limit parameter. (Hint: "a,b,c".split(",", 2) comes out to ["a", "b"], not ["a", "b,c"].)

One would 1st call the string's · split · method: · var list = ' item 1, item 2 , ,item 3 '; · var array = list · .split(','); · gs.debug('\n[' + array.join(']\n[') + ']'); · This prints: · *** Script: [DEBUG] · [ item 1] · [ item 2 ] · [ ] · [item 3 ] · Pretty all over the place. · For better result - where the leading and trailing spaces are removed - one would use · trim · before splitting: · var list = ' item 1, item 2 , ,item 3 '; · var array = list · .trim() · .split(','); · gs.debug('\n[' + array.join(']\n[') + ']'); · *** Script: [DEBUG] · [item 1] · [ item 2 ] · [ ] · [item 3] · Really only slightly better - only the 1st and the last items look good - and half of both only by chance (the one who entered the list did not add extra spaces after the last item and before the 1st one). · To take care of all extra spaces for all items that could exist due to sloppy fellow programmers composing the list or faulty data entry, one would switch the splitter to · RegExp · : · var list = ' item 1, item 2 , ,item 3 '; · var array = list · .trim() · .split(/\s*,\s*/g); · gs.debug('\n[' + array.join(']\n[') + ']'); · *** Script: [DEBUG] · [item 1] · [item 2] · [] · [item 3] · A lot better, almost there, just one problem remains: the 3rd item which is empty. · To take care of that problem one might · filter · the resulting array: · var list = ' item 1, item 2 , ,item 3 '; · var array = list · .trim() · .split(/\s*,\s*/g) · .filter(retainNotEmpty); · function retainNotEmpty (item) { · return '' != item; · } · gs.debug('\n[' + array.join(']\n[') + ']');​ · *** Script: [DEBUG] · [item 1] · [item 2] · [item 3] · Just about what one desires. · Filtering will also fix the issue of empty string ending up (not in a 0 length array, but) in an array with one item when split.

If your variable is an array, you can use -join without needing a loop. PS > $test = @("one","two","three","four") PS > $test one two three four PS > $test -join "," one,two,three,four