Array.prototype.join()
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.
Syntax
join()
join(separator)
Parameters
separatoroptional- : 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
separatoris an empty string, all elements are joined without any characters in between them.
- : 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
Return value
A string with all array elements joined. If arr.length is
0, the empty string is returned.
Description
The string conversions of all array elements are joined into one string. If an element is undefined, null, it is converted to an empty string instead of the string "null" or "undefined".
The join method is accessed internally by Array.prototype.toString() with no arguments. Overriding join of an array instance will override its toString behavior as well.
When used on sparse arrays, the join() method iterates empty slots as if they have the value undefined.
The join() method is generic. It only expects the this value to have a length property and integer-keyed properties.