Using Rest Parameters in TypeScript Functions

In TypeScript, you can use the spread operator (…) as the final parameter of a function. All of the arguments (except the ones that were explicitly declared before the three dots) passed to that function will be taken and placed in an array.

Words may be confusing and non-intuitive. The example below will make things much clearer.

Example:

const example = (name: string, age: number, ...skills: string[]): void => {
  console.log(`Hello ${name}`);
  console.log(`You are ${age} years old`);
  skills.map(skill => {
    console.log(`You can code in ${skill}`)
  })
}

// Invoke the function
example('John Doe', 41, 'Javascript', 'PHP', 'C', 'Java');

Output:

Hello John Doe
You are 41 years old
You can code in Javascript
You can code in PHP
You can code in C
You can code in Java

Further reading:

• TypeScript: Function with Optional and Default Parameters
• Express + TypeScript: Extending Request and Response objects
• Calculate Variance and Standard Deviation in Javascript
• Javascript: Capitalize the First Letter of Each Word (Title Case)
• Javascript: Looping through Keys/Values of an Object

You can also check out our TypeScript category page for the latest tutorials and examples.