Passing arguments forward to another javascript function

Question

I've tried the following with no success:

function a(args){     b(arguments); }  function b(args){     // arguments are lost? }  a(1,2,3); 

In function a, I can use the arguments keyword to access an array of arguments, in function b these are lost. Is there a way of passing arguments to another javascript function like I try to do?

Answer 1

Use .apply() to have the same access to arguments in function b, like this:

console.log = function(x) { document.write(x === undefined ? undefined : JSON.stringify(x) + "<br />"); };  function a(){     b.apply(null, arguments); } function b(){     console.log(arguments); //arguments[0] = 1, etc } a(1,2,3);

You can test it out here.

Answer 2

Spread operator

The spread operator allows an expression to be expanded in places where multiple arguments (for function calls) or multiple elements (for array literals) are expected.

ECMAScript ES6 added a new operator that lets you do this in a more practical way: ...Spread Operator.

Example without using the apply method:

function a(...args){    b(...args);    b(6, ...args, 8) // You can even add more elements  }  function b(){    console.log(arguments)  }    a(1, 2, 3)

Note This snippet returns a syntax error if your browser still uses ES5.

^{Editor's note: Since the snippet uses console.log(), you must open your browser's JS console to see the result - there will be no in-page result.}

It will display this result:

In short, the spread operator can be used for different purposes if you're using arrays, so it can also be used for function arguments, you can see a similar example explained in the official docs: Rest parameters