EN
TypeScript - replace part of string from given index
0 points
In this article, we're going to have a look at how to replace part of a string from a given index in TypeScript.
Quick solution:
xxxxxxxxxx1
const text: string = 'This is text.';2
const index: number = 2;3
const insert: string = '__';4
5
const result: string = text.substring(0, index) + insert + text.substring(index + insert.length);6
7
console.log(result); // Th__ is text.
Presented in this section solution allows inserting text outside of given string filling space with any characters (by default with space).
xxxxxxxxxx1
const repeatText = (count: number, text: string): string => {2
let result = '';3
for (let i = 0; i < count; ++i) {4
result += text;5
}6
return result;7
};8
9
const replaceText = (text: string, insert: string, index: number, spacer?: string): string => {10
if (spacer == null) {11
spacer = ' ';12
}13
const prefix = text.substring(0, index);14
const postfix = text.substring(index + insert.length);15
const space = repeatText(index - text.length, spacer);16
17
return prefix + space + insert + postfix;18
};19
20
21
// Usage example:22
23
console.log(replaceText('This is text.', '__', 0)); // __is is text.24
console.log(replaceText('This is text.', '__', 2)); // Th__ is text.25
console.log(replaceText('This is text.', '__', 11)); // This is tex__26
27
console.log(replaceText('This is text.', '__', 13)); // This is text.__28
console.log(replaceText('This is text.', '__', 15)); // This is text. __29
30
console.log(replaceText('text...', '__', 10, '++')); // text...++++++__Output:
xxxxxxxxxx1
__is is text.2
Th__ is text.3
This is tex__4
This is text.__5
This is text. __6
text...++++++__ES 2015 introduced repeat() method for string.
xxxxxxxxxx1
const replaceText = (text: string, insert: string, index: number, spacer: string = ' '): string => {2
const prefix = text.substring(0, index);3
const postfix = text.substring(index + insert.length);4
const space = spacer.repeat(index < text.length ? 0 : index - text.length);5
6
return prefix + space + insert + postfix;7
};8
9
10
// Usage example:11
12
console.log(replaceText('This is text.', '__', 0)); // __is is text.13
console.log(replaceText('This is text.', '__', 2)); // Th__ is text.14
console.log(replaceText('This is text.', '__', 11)); // This is tex__15
16
console.log(replaceText('This is text.', '__', 13)); // This is text.__17
console.log(replaceText('This is text.', '__', 15)); // This is text. __18
19
console.log(replaceText('text...', '__', 10, '++')); // text...++++++__Output:
xxxxxxxxxx1
__is is text.2
Th__ is text.3
This is tex__4
This is text.__5
This is text. __6
text...++++++__