TypeScript - get first n characters of string

In this short article, we would like to show you how to get the first n characters of a string in TypeScript.

The below example shows the use of .substring() method which returns the part of a string between the 0 and n indexes.

Runnable example:

xxxxxxxxxx

const text: string = '12345';

​

const n: number = 3;

const substring: string = text.substring(0, n);

​

console.log('text: ' + text); // 12345

console.log('substring: ' + substring); // 123

Output:

xxxxxxxxxx

text: 12345

substring: 123

In the second example, we can see the result when we want to get a substring from a string in constious cases (like a string shorter than the number of characters we want to get or an empty string).

Runnable example:

xxxxxxxxxx

// true means string is empty

​

console.log(''.substring(0, 3) === ''); // empty

console.log('1'.substring(0, 3)); // 1

console.log('12'.substring(0, 3)); // 12

console.log('123'.substring(0, 3)); // 123

console.log('1234'.substring(0, 3)); // 123

console.log('12345'.substring(0, 3)); // 123

Output:

xxxxxxxxxx

true

1

12

123

123

123

Note:
Don't use substr() because it's a non-standard method.