Convert arguments to Array
The arguments object thats automatically available within functions can be a source of confusion for some people; it's kind of an array but it's kinda not. JavaScript is awesome in that you can pass any number of arguments to a function, and oftentimes developers need to iterate over every argument provided. The arguments object doesn't have a forEach method, but using a quick JavaScript technique, you can convert arguments to an array:
function myFn(/* any number of arguments */) {
var args = Array.prototype.slice.call(arguments);
// or [].slice.call(arguments)
args.forEach(function(arg) {
// do something with args here
});
}
Much like converting a NodeList to an array, Array's slice method takes the arguments object and converts it to a true array, allowing for forEach, map, and traditional array iteration. Keep that trick up your sleeve for future development.
If you’re using Firefox, or in the future when other browsers support ES6, you can do it more elegantly:
function myFn(...args) { /* code */ }In case you are using Mootools,
Array.fromdoes the job, isn’t it ?Why not it:
You can do that but be aware if you do something like:
function x(){ return Array.apply(null, arguments); }; x(10); //=> it will return empty array with a length of 10 instead of [10]Cool trick, but why even
typeof argumentsreturnsobject?We have a new method,
Array.from(arguments)