JavaScript String charCodeAt()

JavaScript String charCodeAt() Example

Let's take a look at a simple example:

let myString = "Hello, World!";
let unicodeValue = myString.charCodeAt(0);
console.log(unicodeValue);

In this example, charCodeAt(0) will return 72, the Unicode value for the character 'H'.

Output

It's important to note that if the index is out of range (negative, or greater than or equal to the length of the string), charCodeAt() returns NaN.

Let's take another example.

let str = "JavaScript";
let index = 3; // Index of 'a'
let unicodeValue = str.charCodeAt(index);
console.log(unicodeValue); // Output: 97

In this example, the charCodeAt() method retrieves the Unicode value of the character at index 3 in the string "JavaScript", which is the letter 'a'. The Unicode value of 'a' is 97, so the output will be 97.

Practical Application of String charCodeAt()

Understanding the Unicode value of characters can be very useful. For example, it can be used to sort strings in alphabetical order, or to transform lower-case letters to upper-case, and vice versa.

Here is a simple function that converts a lower-case string to upper-case using charCodeAt():

function toUpperCase(str) {
    let result = '';
    for (let i = 0; i < str.length; i++) {
        let charCode = str.charCodeAt(i);
        if(charCode > 96 && charCode < 123) {
            result += String.fromCharCode(charCode - 32);
        } else {
            result += str[i];
        }
    }
    return result;
}
console.log(toUpperCase('hello world')); 

Outputs: 

Frequently Asked Questions

What is String.fromCharCode()?

String.fromCharCode() is a JavaScript method that converts Unicode values (character codes) into a string of corresponding characters.

What is charCode in JavaScript?

charCode refers to the numeric Unicode value representing a character. It can be obtained using methods like charCodeAt() or keyCode in events.

How to get charCode from a string?

Use the charCodeAt(index) method on a string to get the Unicode value of the character at a specific index.

console.log("A".charCodeAt(0)); // Output: 65  

Conclusion

The charCodeAt() JavaScript method is a powerful tool for working with strings. It provides a straightforward way to retrieve the Unicode value of characters in a string. Knowing how and when to use it will certainly enhance your string manipulation skills in JavaScript, making your programs more robust and dynamic.

To learn more about JavaScript, we recommend reading the following articles:

• An Introduction to Javascript
• Resource Loading in JavaScript
• Object Oriented Programming In JavaScript.