Today I learnt about another ES6 feature called rest parameters. As MDN puts it, rest parameter syntax allows us to represent an indefinite number of arguments as an array.
Rest parameters in ES6 are used as in example below, the key is declaring the last paramter in function parameter list with a preceding ... such as ...a. This turns a into array that contains the rest of the parameters in an array.
function f (x, y, ...a) {
return a;
}
f(1, 2, "hello", true, 7); // ["hello", true, 7]The above example can be written in ES5 as well but it's slightly more cumbersome and confusing syntax, as can be seen in the example below.
function f (x, y) {
var a = Array.prototype.slice.call(arguments, 2);
return a;
};
f(1, 2, "hello", true, 7); // ["hello", true, 7]