How to join JavaScript array of string

We need to write a JavaScript function that joins an array of strings, replaces all whitespaces with dashes "-", and returns the formatted string.

For example: If the array is ?

const arr = ["QA testing promotion ", " Twitter ", "Facebook ", "Test"];

Then the output should be ?

const output = "QA-testing-promotion-Twitter-Facebook-Test";

Method 1: Using Loop and String Concatenation

This approach joins the array elements and processes each character to replace spaces with dashes:

const arr = ["QA testing promotion ", " Twitter ", "Facebook ", "Test"];

const joinArr = arr => {
    const arrStr = arr.join('');
    let res = '';
    for(let i = 0; i 

QA-testing-promotion-Twitter-Facebook-Test


Method 2: Using join() and Regular Expression

A more concise approach using built-in string methods:

const arr = ["QA testing promotion ", " Twitter ", "Facebook ", "Test"];

const joinArrSimple = arr => {
    return arr.join('').trim().replace(/\s+/g, '-');
};

console.log(joinArrSimple(arr));


QA-testing-promotion-Twitter-Facebook-Test


Method 3: Using map() and filter()

Clean approach that handles each array element separately:

const arr = ["QA testing promotion ", " Twitter ", "Facebook ", "Test"];

const joinArrClean = arr => {
    return arr
        .map(str => str.trim())
        .filter(str => str.length > 0)
        .join(' ')
        .replace(/\s+/g, '-');
};

console.log(joinArrClean(arr));


QA-testing-promotion-Twitter-Facebook-Test


Comparison

Key Points

• join('') combines array elements without separators
• trim() removes leading and trailing whitespace
• /\s+/g regex matches one or more consecutive spaces
• replace() substitutes matched patterns with dashes

Conclusion

The regular expression method provides the cleanest and most efficient solution for joining string arrays and replacing spaces with dashes. Use join('').trim().replace(/\s+/g, '-') for the best results.