In this tutorial, we will learn how to split String into Substrings of N characters in JavaScript.

So to split string by length of N character in javascript, we will use the following methods

1. Using String.split() and regex
2. Using String.match() and regex
3. Using substr()

Split a string by length of N characters using split()

The split() method is used to split a string into an array of substrings and return us a new array.

To split a string into substrings with the length of N character, we will use the following regular expression /.{1, N}/g.

var str = "123456"

const result = str.split(/(.{1,2})/g).filter(x => x)
console.log(result) // [ '12', '34', '56' ]

Here, we have used regex to split the string into a specific length of chunks/substring.

The / / (forward slash) is the beginning and end of a regex expression.

The . is used to find a single character in the string except the newline or line terminator.

The g (global) flag is used to perform a global match. It finds all matches in the string rather than stopping after the first match.

The expression {1,2} is used to tell the program the range, here at least 1 or at most 2 of the succeeding characters in the string.

The filter(x=>x) is used to filter out empty elements which is created between chunks while using regex.

Read more about regular expression here : Regular expression syntax cheatsheet – JavaScript | MDN

Split String to Substring of N character using match()

const str = "123456".match(/.{1,2}/g);
console.log(str) //[ '12', '34', '56' ]

The String.match() method is used to search a string for a match against a regular expression. If a match is found it will return it in an array.

If the match is not found, it will return null.

We can create a reuasble function like this,

function splitString(str, length) {
  return str.match(new RegExp('.{1,' + length + '}', 'g')) || [];
}

console.log(splitString('1450s',2)),2)) //[ '14', '50', 's' ]

Since match() method returns null when a match is not found in the string. So we have used the || (logical OR) to return an empty array ([]) instead of null .

If you don’t want to use regular expressions for this, we can use a loop with substr().

Split a String into a Substring using substr() method

We will use the for loop method to split the string into sub-string with the length of N character.

Example:

function splitStrings(str, n) {
  const arr = [];
  for (let index = 0; index < str.length; index += n) {
    arr.push(str.substr(index, n));
  }
  return arr;
}

console.log(splitStrings('abcd1234ABCD8976', 4));

Output:

[ 'abcd', '1234', 'ABCD', '8976' ]

Here, we have a function with takes in two parameters, string and the length of the substring.

We have used for loop to iterate over the string with the increment of N to the index value.

And on each iteration, we have extracted the characters of N length from the string using substr() method and push it into our empty array.

The substr() method takes in two parameters and its syntax is

string.substr(start, length)

start : The start position from where we want to extract from the string.

length : The number of characters we want to extract.

Once the loop has extracted the characters from the string we return the array of substrings.

Conclusion: Using the split(), match() and, substr() method, we can split a string into substrings of n characters easily in JavaScript. Regex can perform the task will one line of code, however, if you don’t like using regex, you can go for the for loop method.

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