Get the first 4 numbers of a string in JavaScript

In this tutorial, we will learn how to get the first 4 numbers of a string in JavaScript.

In JavaScript, strings are the sequence of characters, where the index of the first character is 0, the second character is 1, third character is 3 etc.

Getting the first 4 numbers of a string

To get the first 4 numbers of a string, we can use the built-in slice() method by passing 0, 4 as an arguments to it.

Here is an example:

const id = "2345john23";

const firstFourNumbers = id.silce(0, 4);
console.log(firstFourNumbers);

Output:

"2345"

In the example above, we have passed 0, 4 as an arguments to the slice() method. so it begins the extraction at index 0 and extracts before the index 4 of a string.

The slice() method takes the two arguments, the first argument is start index and the second argument is end index then it returns a new string between the start index and end index (that is excluded from the output).

Similarly, we can also use the String.match() method by passing the regular expression /\d{4}/ to get the first 4 numbers from a string.

Here is an example:

const id = "2345john23";

const firstFourNumbers = id.match(/\d{4}/)[0];
console.log(firstFourNumbers); // 2345

The regular expression /\d{4}/, where d matches the numbers ranging from 0 to 9 and extracts thw first 4 characters anywhere from the string.