TypeScript - replace last character in string
In this article, we're going to have a look at how to replace the last character from the string in TypeScript.
1. String slice() method example
This approach allows getting substring by using negative indexes. So by using 0 and -1 indexes as the range we get <0, text.length - 1> text range. Then, we add the replacement at the end of the result string to replace the missing character.
const text: string = 'ABC';
const replacement: string = 'x';
const result: string = text.slice(0, -1) + replacement;
console.log(result); // ABx
Output:
ABx
2. String substring() method example
This is an alternative approach to slice method based solution. We remove the last character to add the replacement at the end of the result string to replace the missing character.
const text: string = 'ABC';
const replacement: string = 'x';
const result: string = text.substring(0, text.length - 1) + replacement;
console.log(result); // ABx
Output:
ABx
3. String replace() method example
There is another trick that allows replacing all characters that match expression conditions with an empty string. By using .$ pattern we match any character that is located at the end of the string.
const text: string = 'ABC';
const replacement: string = 'x';
const result: string = text.replace(/.$/, replacement);
console.log(result); // ABx
Output:
ABx