Easy way to turn JavaScript array into comma-separated list?

The Array.prototype.join() method:

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

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

Actually, the toString() implementation does a join with commas by default:

var arr = [ 42, 55 ];
var str1 = arr.toString(); // Gives you "42,55"
var str2 = String(arr); // Ditto

I don't know if this is mandated by the JS spec but this is what most pretty much all browsers seem to be doing.

Or (more efficiently):

var arr = new Array(3);
arr[0] = "Zero";
arr[1] = "One";
arr[2] = "Two";

document.write(arr); // same as document.write(arr.toString()) in this context

The toString method of an array when called returns exactly what you need - comma-separated list.

Simple Array

let simpleArray = [1,2,3,4]
let commaSeperated = simpleArray.join(",");
console.log(commaSeperated);

Array of Objects with a particular attributes as comma separated.

let arrayOfObjects = [
{
id : 1,
name : "Name 1",
address : "Address 1"
},
{
id : 2,
name : "Name 2",
address : "Address 2"
},
{
id : 3,
name : "Name 3",
address : "Address 3"
}]
let names = arrayOfObjects.map(x => x.name).join(", ");
console.log(names);

Result

Name 1, Name 2, Name 3

const arr = [1, 2, 3];
console.log(`${arr}`)

I liked the solution at https://jsfiddle.net/rwone/qJUh2/ because it adds spaces after commas:

array = ["test","test2","test3"]
array = array.toString();
array = array.replace(/,/g, ", ");
alert(array);

Or, as suggested by @StackOverflaw in the comments:

array.join(', ');

As of Chrome 72, it's possible to use Intl.ListFormat:

const vehicles = ['Motorcycle', 'Bus', 'Car'];

const formatter = new Intl.ListFormat('en', { style: 'long', type: 'conjunction' });
console.log(formatter.format(vehicles));
// expected output: "Motorcycle, Bus, and Car"

const formatter2 = new Intl.ListFormat('de', { style: 'short', type: 'disjunction' });
console.log(formatter2.format(vehicles));
// expected output: "Motorcycle, Bus oder Car"

const formatter3 = new Intl.ListFormat('en', { style: 'narrow', type: 'unit' });
console.log(formatter3.format(vehicles));
// expected output: "Motorcycle Bus Car"

Please note that this way is in its very earlier stage, so as of the date of posting this answer, expect incompatibility with older versions of Chrome and other browsers.

here you can separate with any char and can take any property list with just foreach

let taskIds: string = '';    
this.checkedTaskList.forEach(res => {
  taskIds = taskIds + res.taskId.toString() + ','
});
if (taskIds) {
    taskIds.substring(0, taskIds.length - 1),**
}

Safe way for string that contains separator (comma)

let arr = ["Hello, there", "How's there", 'the "best"']
let csv = arr.map(e => JSON.stringify(e)).join(",")
console.log(csv)

result

"Hello, there","How's there","the \\"best\\""

This solution also removes values such as " ":

const result = ['', null, 'foo', '  ', undefined, 'bar'].filter(el => {
  return Boolean(el) && el.trim() !== '';
}).join(', ');

console.log(result); // => foo, bar