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
position: is a required parameter; represents the position of the character.
Function
A sample use of charAt is:
charAt(str:string)
{
var position = str.charAt(0);
var span = document.createElement("span");
span.innerText = "charAt Method \n Display the first character of a string-> " + position + "\n";
document.body.appendChild(span);
}
charCodeAt() Method
In TypeScript the charCodeAt() method is returns a number that represents the Unicode value of the character at the given position.
Syntax
|
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:
charCodeAt(str:string)
{
var unicode = str.charCodeAt(str.length-1);
var span = document.createElement("span");
span.style.color = "green";
span.innerText = "charCodeAt Method \n Display the unicode of the last character in a string-> " + unicode + "\n";
document.body.appendChild(span);
}
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
class charAt_charCodeAt
{
charAt(str:string)
{
var position = str.charAt(0);
var span = document.createElement("span");
span.innerText = "charAt Method \n Display the first character of a string-> " + position + "\n";
document.body.appendChild(span);
}
charCodeAt(str:string)
{
var unicode = str.charCodeAt(str.length-1);
var span = document.createElement("span");
span.style.color = "green";
span.innerText = "charCodeAt Method \n Display the unicode of the last character in a string-> " + unicode + "\n";
document.body.appendChild(span);
}
}
window.onload = () =>
{
var obj = new charAt_charCodeAt();
var str = prompt("Please enter a string");
obj.charAt(str);
obj.charCodeAt(str);
};
chatAt_charCodeAt_MethodDemo.htm
<!DOCTYPE html>
<html lang="en" xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta charset="utf-8" />
<title>TypeScript HTML App</title>
<link rel="stylesheet" href="app.css" type="text/css" />
<script src="charAt_charCodeAt.js"></script>
</head>
<body>
<h3>charAt() and charCodeAt() String Object Method In TypeScript</h3>
<div id="content"/>
</body>
</html>
chatAt_charCodeAt.js
var charAt_charCodeAt = (function () {
function charAt_charCodeAt() { }
charAt_charCodeAt.prototype.charAt = function (str) {
var position = str.charAt(0);
var span = document.createElement("span");
span.innerText = "charAt Method \n Display the first character of a string-> " + position + "\n";
document.body.appendChild(span);
};
charAt_charCodeAt.prototype.charCodeAt = function (str) {
var unicode = str.charCodeAt(str.length - 1);
var span = document.createElement("span");
span.style.color = "green";
span.innerText = "charCodeAt Method \n Display the unicode of the last character in a string-> " + unicode + "\n";
document.body.appendChild(span);
};
return charAt_charCodeAt;
})();
window.onload = function () {
var obj = new charAt_charCodeAt();
var str = prompt("Please enter a string");
obj.charAt(str);
obj.charCodeAt(str);
};
//@ sourceMappingURL=charAt_charCodeAt.js.map
Output 1
Enter a string and click on "Ok":
![enter-string.jpg]()
Output 2
![result.jpg]()