String Object Method In TypeScript: Part 1

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

string.charAt(position)

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 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);
};

Output 1

Enter a string and click on "Ok":

Output 2