Static Utility Methods
Part of the Object Oriented Programming section of Coddy's JavaScript journey — lesson 33 of 56.
Static methods are utility functions that belong to the class itself rather than to instances of the class. They're useful for functions that don't require access to instance-specific data.
Let's create a class with a static utility method:
class MathHelper {
// Define a static method
static square(number) {
return number * number;
}
}To call a static method, you use the class name directly:
// Call the static method without creating an instance
const result = MathHelper.square(5);
console.log(result); // 25Notice we didn't need to create a new instance with new MathHelper(). Static methods are perfect for utility functions that perform operations without needing instance data.
Challenge
Create a class named StringUtils with a static method called capitalize that takes a string as an argument and returns the same string with the first letter capitalized. For example, if the input is "javascript", the method should return "Javascript". Export this class.
- Check if the string is empty:
if (!str || str.length === 0)(Without this check an empty string could cause issues).!strchecks fornull/undefined(prevents errors)str.length === 0checks for empty string (returns "" instead of crashing)
- Get the first character:
str.charAt(0) - Make it uppercase:
.toUpperCase() - Get the rest of the string:
str.slice(1)(from position 1 to end) - Combine: uppercase first character + rest of string
Cheat sheet
Static methods are utility functions that belong to the class itself rather than to instances. They don't require access to instance-specific data.
Define a static method using the static keyword:
class MathHelper {
static square(number) {
return number * number;
}
}Call static methods directly on the class without creating an instance:
const result = MathHelper.square(5);
console.log(result); // 25Useful string methods for static utilities:
str.charAt(0)- gets the first characterstr.toUpperCase()- converts to uppercasestr.slice(1)- gets substring from position 1 to end!str || str.length === 0- checks for null/undefined or empty string
Try it yourself
import { StringUtils } from './stringUtils.js';
// Don't modify the code below
console.log(StringUtils.capitalize("programming"));
Test yourselfThis lesson includes a short quiz. Start the lesson to answer it and track your progress.
All lessons in Object Oriented Programming
1Objects & The this Keyword
Quick Review: ObjectsAdding Methods to ObjectsUnderstanding the this KeywordConstructor FunctionsThe new KeywordRecap Challenge7 Inheritance & The extends Key
InheritanceThe "is-a" RelationshipThe extends KeywordThe super() MethodInheriting Properties&MethodsRecap Challenge2Organizing Code
What are Modules?Exporting with exportImporting with importDefault vs. Named Exports8Organizing OOP Code
Organize Classes into Modules11Project: A Shape Renderer
Setup: Shape Class & ExportCircle Class Inheritance
Overriding & Area MethodStatic Shape Counter9Static Methods & Properties
Class-Level vs. Instance-LevelStatic PropertiesStatic Utility MethodsRecap challenge