Back
Syntax
Study
Editor
Mode:
HTML
CSS
JavaScript
PHP
Reset
Run »
HTML / CSS / JS
// Typed parameters and return type function add(a: number, b: number): number { return a + b; } // Optional and default parameters function greet(name: string, greeting: string = 'Hello'): string { return `${greeting}, ${name}!`; } // Rest parameters function sum(...nums: number[]): number { return nums.reduce((acc, n) => acc + n, 0); } // Function type type MathOp = (a: number, b: number) => number; const multiply: MathOp = (a, b) => a * b; // Void return (no return value) function logMessage(msg: string): void { console.log(`[LOG] ${msg}`); } // Overloads function format(value: string): string; function format(value: number): string; function format(value: string | number): string { return typeof value === 'number' ? value.toFixed(2) : value.trim(); } // Generic function function first<T>(arr: T[]): T | null { return arr.length > 0 ? arr[0] : null; }
Result
Open