revision:
The join() method creates and returns a new string by concatenating all of the elements in an array (or an array-like object), separated by commas or a specified separator string. If the array has only one item, then that item will be returned without using the separator.
The join() method returns an array as a string. It does not change the original array. Any separator can be specified. The default is comma (,).
array.join() array.join(separator)
Parameters:
separator : optional. Specifies a string to separate each pair of adjacent elements of the array. The separator is converted to a string if necessary. If omitted, the array elements are separated with a comma (","). If separator is an empty string, all elements are joined without any characters in between them.
const elements = ['Fire', 'Air', 'Water']; console.log(elements.join()); // Expected output: "Fire,Air,Water" console.log(elements.join('')); // Expected output: "FireAirWater" console.log(elements.join('-')); // Expected output: "Fire-Air-Water"
<div> <p id="join-1"></p> <p id="join-2"></p> <p id="join-3"></p> </div> <script> const matrix = [ [1, 2, 3], [4, 5, 6], [7, 8, 9], ]; console.log(matrix.join()); // 1,2,3,4,5,6,7,8,9 console.log(matrix.join(";")); // 1,2,3;4,5,6;7,8,9 document.getElementById("join-1").innerHTML = "matrix.join:" + matrix.join(); document.getElementById("join-2").innerHTML = "matrix.join:" + matrix.join(''); document.getElementById("join-3").innerHTML = "matrix.join:" + matrix.join(' - '); </script>
<div> <p id="join-4"></p> <p id="join-5"></p> <p id="join-6"></p> <p id="join-7"></p> </div> <script> const a = ["Wind", "Water", "Fire"]; console.log(a.join()); // 'Wind,Water,Fire' console.log(a.join(", ")); // 'Wind, Water, Fire' console.log(a.join(" + ")); // 'Wind + Water + Fire' console.log(a.join("")); // 'WindWaterFire' document.getElementById("join-4").innerHTML = "words.join:" + a.join(); document.getElementById("join-5").innerHTML = "words.join:" + a.join(", "); document.getElementById("join-6").innerHTML = "words.join:" + a.join(" + "); document.getElementById("join-7").innerHTML = "words.join:" + a.join(""); </script>
join() returns an array as a string:
<div> <p>join() returns an array as a string:</p> <p id="join-8"></p> <p id="join-9"></p> </div> <script> const fruits = [" Banana", " Orange", " Apple", " Mango"]; let text = fruits.join(); document.getElementById("join-8").innerHTML = "fruits : " + text; let text2 = fruits.join(" and "); document.getElementById("join-9").innerHTML = "fruits : " + text2; </script>