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.
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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)