Join

:::info[Note] This is a point-in-time snapshot of the API documentation from January 2026. Going forward, we will not be maintaining a public copy of these references, and recommend users to refer to the built-in signature helpers available in the Hack LSP instead for complete and up-to-date information. :::

Returns a string formed by joining the elements of the Traversable with the given $glue string

namespace HH\Lib\Str;

function join(
  Traversable<arraykey> $pieces,
  string $glue,
): string;

Previously known as implode in PHP.

Guide

• String

Parameters

• Traversable<arraykey>$pieces
• string $glue

Returns

• string

Examples

$strings= vec["a", "b", "c", "d"];

$joined_string_1 = Str\join($strings, ",");
echo "First string: $joined_string_1 \n";

$joined_string_2 = Str\join($strings, "-");
echo "Second string: $joined_string_2";