Learn Joining Array Elements with join | Functional Patterns and Utilities

The join method in JavaScript is a powerful tool for converting arrays into strings. It works by concatenating all the elements of an array, inserting a specified separator between each element. This is especially useful when you need to present array data in a human-readable format, such as displaying a list of items separated by commas, spaces, or custom characters. Using join can help you create neatly formatted output for user interfaces, logs, or data exports.


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const words = ["JavaScript", "arrays", "are", "powerful"];
console.log(words.join(" ")); // JavaScript arrays are powerful
console.log(words.join(", ")); // JavaScript, arrays, are, powerful
console.log(words.join(" - ")); // JavaScript - arrays - are - powerful
console.log(words.join("")); // JavaScriptarraysarepowerful

Note

There is a key difference between the join and toString methods for arrays. While both convert arrays to strings, join lets you specify a custom separator, but toString always uses a comma. This makes join much more flexible for formatting array output exactly as you need.

1. What will be the result of the following code?

2. Fill in the blank to join the array elements with a slash ("/") so that the output is "2024/6/10".

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Section 4. Chapter 3

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