The rest parameter is an improved way to handle function parameters, allowing us to more easily handle various inputs as parameters in a function. The rest parameter syntax allows us to represent an indefinite number of arguments as an array. With the help of a rest parameter, a function can be called with any number of arguments, no matter how it was defined. Rest parameter is added in ES2015 or ES6 which improved the ability to handle parameter.

Syntax: 

//… is the rest parameter (triple dots) function functionname(…parameters) { statement; }

Note: The rest parameter has to be the last argument, as its job is to collect all the remaining arguments into an array. So having a function definition like the code below doesn’t make any sense and will throw an error.