JavaScript: Join all elements of an array into a string and returns this string
JavaScript fundamental (ES6 Syntax): Exercise-182 with Solution
Write a JavaScript program to join all elements of an array into a string and returns this string.
Uses a separator and an end separator.
- Use Array.prototype.reduce() to combine elements into a string.
- Omit the second argument, separator, to use a default separator of ','.
- Omit the third argument, end, to use the same value as separator by default.
Sample Solution:
JavaScript Code:
//#Source https://bit.ly/2neWfJ2
const join = (arr, separator = ',', end = separator) =>
arr.reduce(
(acc, val, i) =>
i === arr.length - 2
? acc + val + end
: i === arr.length - 1
? acc + val
: acc + val + separator,
''
);
console.log(join(['pen', 'pineapple', 'apple', 'pen'], ',', '&'));
console.log(join(['pen', 'pineapple', 'apple', 'pen'], ','));
console.log(join(['pen', 'pineapple', 'apple', 'pen']));
Sample Output:
pen,pineapple,apple&pen pen,pineapple,apple,pen pen,pineapple,apple,pen
Pictorial Presentation:
Flowchart:

Live Demo:
See the Pen javascript-basic-exercise-182-1 by w3resource (@w3resource) on CodePen.
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