Introduction

The String object is used to manage a series of characters. The String object contains complete information about strings. In TypeScript, String objects are created with "new String()".
In this article, I am describing the TypeScript charAt and charCodeAt string methods.

chatAt() Method

In TypeScript, the charAt() method returns the character at the specified position in the string. Characters in a string proceed (are indexed) from left to right. The position of the first character is 0 and the position of the last character in a string is string.length - 1.
Syntax
  1. string.charAt(position)
position: is a required parameter; represents the position of the character.
Function
A sample use of charAt is:
  1. charAt(str: string) {
  2. var position = str.charAt(0);
  3. var span = document.createElement("span");
  4. span.innerText = "charAt Method \n Display the first character of a string-> " + position + "\n";
  5. document.body.appendChild(span);
  6. }

charCodeAt() Method

In TypeScript the charCodeAt() method returns a number that represents the Unicode value of the character at the given position.
Syntax
  1. string.charCodeAt(position)
position: is a required parameter; the position value is between 0 and the position of the last character, which is 1 less than the length of the string. The default position is 0.
Function
A sample use of charCodeAt is:
  1. charCodeAt(str: string) {
  2. var unicode = str.charCodeAt(str.length - 1);
  3. var span = document.createElement("span");
  4. span.style.color = "green";
  5. span.innerText = "charCodeAt Method \n Display the unicode of the last character in a string-> " + unicode + "\n";
  6. document.body.appendChild(span);
  7. }
The following example shows how to use charAt and charCodeAt methods in TypeScript. In this example, we get a string from the user. The charAt() method returns the character at the specified position and the charCodeAt() method returns a Unicode character at a specified index.

Complete Program

chatAt_charCodeAt.ts
  1. class charAt_charCodeAt {
  2. charAt(str: string) {
  3. var position = str.charAt(0);
  4. var span = document.createElement("span");
  5. span.innerText = "charAt Method \n Display the first character of a string-> " + position + "\n";
  6. document.body.appendChild(span);
  7. }
  8. charCodeAt(str: string) {
  9. var unicode = str.charCodeAt(str.length - 1);
  10. var span = document.createElement("span");
  11. span.style.color = "green";
  12. span.innerText = "charCodeAt Method \n Display the unicode of the last character in a string-> " + unicode + "\n";
  13. document.body.appendChild(span);
  14. }
  15. }
  16. window.onload = () => {
  17. var obj = new charAt_charCodeAt();
  18. var str = prompt("Please enter a string");
  19. obj.charAt(str);
  20. obj.charCodeAt(str);
  21. };
chatAt_charCodeAt_MethodDemo.htm
  1. < !DOCTYPE html >
  2. <
  3. html lang = "en"
  4. xmlns = "http://www.w3.org/1999/xhtml" >
  5. <
  6. head >
  7. <
  8. meta charset = "utf-8" / >
  9. <
  10. title > TypeScript HTML App < /title>
  11. <
  12. link rel = "stylesheet"
  13. href = "app.css"
  14. type = "text/css" / >
  15. <
  16. script src = "charAt_charCodeAt.js" > < /script>
  17. <
  18. /head>
  19. <
  20. body >
  21. <
  22. h3 > charAt() and charCodeAt() String Object Method In TypeScript < /h3>
  23. <
  24. div id = "content" / >
  25. <
  26. /body>
  27. <
  28. /html>
chatAt_charCodeAt.js
  1. var charAt_charCodeAt = (function() {
  2. function charAt_charCodeAt() {}
  3. charAt_charCodeAt.prototype.charAt = function(str) {
  4. var position = str.charAt(0);
  5. var span = document.createElement("span");
  6. span.innerText = "charAt Method \n Display the first character of a string-> " + position + "\n";
  7. document.body.appendChild(span);
  8. };
  9. charAt_charCodeAt.prototype.charCodeAt = function(str) {
  10. var unicode = str.charCodeAt(str.length - 1);
  11. var span = document.createElement("span");
  12. span.style.color = "green";
  13. span.innerText = "charCodeAt Method \n Display the unicode of the last character in a string-> " + unicode + "\n";
  14. document.body.appendChild(span);
  15. };
  16. return charAt_charCodeAt;
  17. })();
  18. window.onload = function() {
  19. var obj = new charAt_charCodeAt();
  20. var str = prompt("Please enter a string");
  21. obj.charAt(str);
  22. obj.charCodeAt(str);
  23. };
Output 1
Enter a string and click on "Ok":
enter-string.jpg
Output 2
result.jpg