TypeScript - replace first character in string

In this article, we would like to show you how to replace the first character in string in TypeScript.

Quick solution

const text: string = 'ABC';
const result: string = 'x' + text.slice(1);

console.log(result); // xBC

or:

const text: string = 'ABC';
const replacer: string = 'x';

const result: string = replacer.concat(text.slice(1));

console.log(result); // xBC

or:

const text = 'ABC';
const result = text.replace(/^./g, 'x');

console.log(result); // xBC

1. Using string slice() with + operator

In this example, we use string slice() method to remove the first character of the text string. Then with + operator we add the remainder of the text to the replacer.

Runnable example:

const text: string = 'ABC';
const replacer: string = 'x';

const result: string = replacer + text.slice(1);

console.log(result); // xBC

Output:

xBC

Note:

The replacer for the removed character may cosist of any number of characters, not exactly one.

2. Using string slice() with concat() method

In this example, we use string slice() method to remove the first character of the text string. Then with concat() method we add the remainder of the text to the replacer.

Runnable example:

const text: string = 'ABC';
const replacer: string = 'x';

const result: string = replacer.concat(text.slice(1));

console.log(result); // xBC

Output:

xBC

Note:

The replacer for the removed character may cosist of any number of characters, not exactly one.

3. Using string replace() with regex

In this example, we use string replace() with /^./g regex to replace the first character in the text string.

Regex explanation:

• ^ - matches the beginning of the string,
• . - matches any character except linebreaks.

Runnable example:

const text: string = 'ABC';
const result: string = text.replace(/^./g, 'x');

console.log(result); // xBC

Output:

xBC