Return multiple values in JavaScript?

Question

I am trying to return two values in JavaScript. Is this possible?

var newCodes = function() {  
    var dCodes = fg.codecsCodes.rs;
    var dCodes2 = fg.codecsCodes2.rs;
    return dCodes, dCodes2;
};

Answer 1

No, but you could return an array containing your values:

function getValues() {
    return [getFirstValue(), getSecondValue()];
}

Then you can access them like so:

var values = getValues();
var first = values[0];
var second = values[1];

With the latest ECMAScript 6 syntax*, you can also destructure the return value more intuitively:

const [first, second] = getValues();

If you want to put "labels" on each of the returned values (easier to maintain), you can return an object:

function getValues() {
    return {
        first: getFirstValue(),
        second: getSecondValue(),
    };
}

And to access them:

var values = getValues();
var first = values.first;
var second = values.second;

Or with ES6 syntax:

const {first, second} = getValues();

^{* See this table for browser compatibility. Basically, all modern browsers aside from IE support this syntax, but you can compile ES6 code down to IE-compatible JavaScript at build time with tools like Babel.}

Answer 2

You can do this from ECMAScript 6 onwards using arrays and "destructuring assignments". Note that these are not available in older Javascript versions (meaning — neither with ECMAScript 3rd nor 5th editions).

It allows you to assign to 1+ variables simultaneously:

var [x, y] = [1, 2];
x; // 1
y; // 2

// or

[x, y] = (function(){ return [3, 4]; })();
x; // 3
y; // 4

You can also use object destructuring combined with property value shorthand to name the return values in an object and pick out the ones you want:

let {baz, foo} = (function(){ return {foo: 3, bar: 500, baz: 40} })();
baz; // 40
foo; // 3

And by the way, don't be fooled by the fact that ECMAScript allows you to return 1, 2, .... What really happens there is not what might seem. An expression in return statement — 1, 2, 3 — is nothing but a comma operator applied to numeric literals (1 , 2, and 3) sequentially, which eventually evaluates to the value of its last expression — 3. That's why return 1, 2, 3 is functionally identical to nothing more but return 3.

return 1, 2, 3;
// becomes
return 2, 3;
// becomes
return 3;

Answer 3

Just return an object literal

function newCodes(){
    var dCodes = fg.codecsCodes.rs; // Linked ICDs  
    var dCodes2 = fg.codecsCodes2.rs; //Linked CPTs       
    return {
        dCodes: dCodes, 
        dCodes2: dCodes2
    };  
}


var result = newCodes();
alert(result.dCodes);
alert(result.dCodes2);

Answer 4

Since ES6 you can do this

let newCodes = function() {  
    const dCodes = fg.codecsCodes.rs
    const dCodes2 = fg.codecsCodes2.rs
    return {dCodes, dCodes2}
};

let {dCodes, dCodes2} = newCodes()

Return expression {dCodes, dCodes2} is property value shorthand and is equivalent to this {dCodes: dCodes, dCodes2: dCodes2}.

This assignment on last line is called object destructing assignment. It extracts property value of an object and assigns it to variable of same name. If you'd like to assign return values to variables of different name you could do it like this let {dCodes: x, dCodes2: y} = newCodes()

Answer 5

Ecmascript 6 includes "destructuring assignments" (as kangax mentioned) so in all browsers (not just Firefox) you'll be able to capture an array of values without having to make a named array or object for the sole purpose of capturing them.

//so to capture from this function
function myfunction()
{
 var n=0;var s=1;var w=2;var e=3;
 return [n,s,w,e];
}

//instead of having to make a named array or object like this
var IexistJusttoCapture = new Array();
IexistJusttoCapture = myfunction();
north=IexistJusttoCapture[0];
south=IexistJusttoCapture[1];
west=IexistJusttoCapture[2];
east=IexistJusttoCapture[3];

//you'll be able to just do this
[north, south, west, east] = myfunction(); 

You can try it out in Firefox already!

Answer 6

Another worth to mention newly introduced (ES6) syntax is use of object creation shorthand in addition to destructing assignment.

function fun1() {
  var x = 'a';
  var y = 'b';
  return { x, y, z: 'c' };
  // literally means { x: x, y: y, z: 'c' };
}

var { z, x, y } = fun1(); // order or full presence is not really important
// literally means var r = fun1(), x = r.x, y = r.y, z = r.z;
console.log(x, y, z);

This syntax can be polyfilled with babel or other js polyfiller for older browsers but fortunately now works natively with the recent versions of Chrome and Firefox.

But as making a new object, memory allocation (and eventual gc load) are involved here, don't expect much performance from it. JavaScript is not best language for developing highly optimal things anyways but if that is needed, you can consider putting your result on surrounding object or such techniques which are usually common performance tricks between JavaScript, Java and other languages.

Answer 7

function a(){
  var d = 2;
  var c = 3;
  var f = 4;
  return {d: d, c: c, f: f};
}

Then use

const {d, c, f} = a();

In new version:

function a(){
  var d = 2;
  var c = 3;
  var f = 4;
  return {d, c, f}
}

Answer 8

Other than returning an array or an object as others have recommended, you can also use a collector function (similar to the one found in The Little Schemer):

function a(collector){
  collector(12,13);
}

var x,y;
a(function(a,b){
  x=a;
  y=b;
});

I made a jsperf test to see which one of the three methods is faster. Array is fastest and collector is slowest.

http://jsperf.com/returning-multiple-values-2

Answer 9

In JS, we can easily return a tuple with an array or object, but do not forget! => JS is a callback oriented language, and there is a little secret here for "returning multiple values" that nobody has yet mentioned, try this:

var newCodes = function() {  
    var dCodes = fg.codecsCodes.rs;
    var dCodes2 = fg.codecsCodes2.rs;
    return dCodes, dCodes2;
};

becomes

var newCodes = function(fg, cb) {  
    var dCodes = fg.codecsCodes.rs;
    var dCodes2 = fg.codecsCodes2.rs;
    cb(null, dCodes, dCodes2);
};

:)

bam! This is simply another way of solving your problem.

Answer 10

A very common way to return multiple values in javascript is using an object literals, so something like:

const myFunction = () => {
  const firstName = "Alireza", 
        familyName = "Dezfoolian",
        age = 35;
  return { firstName, familyName, age};
}

and get the values like this:

myFunction().firstName; //Alireza
myFunction().familyName; //Dezfoolian
myFunction().age; //age

or even a shorter way:

const {firstName, familyName, age} = myFunction();

and get them individually like:

firstName; //Alireza
familyName; //Dezfoolian
age; //35

Answer 11

You can also do:

function a(){
  var d=2;
  var c=3;
  var f=4;
  return {d:d,c:c,f:f}
}

const {d,c,f} = a()

Answer 12

Adding the missing important parts to make this question a complete resource, as this comes up in search results.

Object Destructuring

In object destructuring, you don't necessarily need to use the same key value as your variable name, you can assign a different variable name by defining it as below:

const newCodes = () => {  
    let dCodes = fg.codecsCodes.rs;
    let dCodes2 = fg.codecsCodes2.rs;
    return { dCodes, dCodes2 };
};

//destructuring
let { dCodes: code1, dCodes2: code2 } = newCodes();

//now it can be accessed by code1 & code2
console.log(code1, code2);

Array Destructuring

In array destructuring, you can skip the values you don't need.

const newCodes = () => {  
    //...
    return [ dCodes, dCodes2, dCodes3 ];
};

let [ code1, code2 ] = newCodes(); //first two items
let [ code1, ,code3 ] = newCodes(); //skip middle item, get first & last
let [ ,, code3 ] = newCodes(); //skip first two items, get last
let [ code1, ...rest ] = newCodes(); //first item, and others as an array

It's worth noticing that ...rest should always be at the end as it doesn't make any sense to destruct anything after everything else is aggregated to rest.

I hope this will add some value to this question :)

Answer 13

You can use "Object"

function newCodes(){
    var obj= new Object();
    obj.dCodes = fg.codecsCodes.rs;
    obj.dCodes2 = fg.codecsCodes2.rs;

    return obj;
}

Answer 14

All's correct. return logically processes from left to right and returns the last value.

function foo(){
    return 1,2,3;
}

>> foo()
>> 3

Answer 15

I would suggest to use the latest destructuring assignment (But make sure it's supported in your environment)

var newCodes = function () {
    var dCodes = fg.codecsCodes.rs;
    var dCodes2 = fg.codecsCodes2.rs;
    return {firstCodes: dCodes, secondCodes: dCodes2};
};
var {firstCodes, secondCodes} = newCodes()

Answer 16

I know of two ways to do this: 1. Return as Array 2. Return as Object

Here's an example I found:

<script>
// Defining function
function divideNumbers(dividend, divisor){
    var quotient = dividend / divisor;
    var arr = [dividend, divisor, quotient];
    return arr;
}

// Store returned value in a variable
var all = divideNumbers(10, 2);

// Displaying individual values
alert(all[0]); // 0utputs: 10
alert(all[1]); // 0utputs: 2
alert(all[2]); // 0utputs: 5
</script>



<script>
// Defining function
function divideNumbers(dividend, divisor){
    var quotient = dividend / divisor;
    var obj = {
        dividend: dividend,
        divisor: divisor,
        quotient: quotient
    };
    return obj;
}

// Store returned value in a variable
var all = divideNumbers(10, 2);

// Displaying individual values
alert(all.dividend); // 0utputs: 10
alert(all.divisor); // 0utputs: 2
alert(all.quotient); // 0utputs: 5
</script>

Answer 17

Few Days ago i had the similar requirement of getting multiple return values from a function that i created.

From many return values , i needed it to return only specific value for a given condition and then other return value corresponding to other condition.

---

Here is the Example of how i did that :

Function:

function myTodayDate(){
    var today = new Date();
    var day = ["Sunday","Monday","Tuesday","Wednesday","Thursday","Friday","Saturday"];
    var month = ["January","February","March","April","May","June","July","August","September","October","November","December"];
    var myTodayObj = 
    {
        myDate : today.getDate(),
        myDay : day[today.getDay()],
        myMonth : month[today.getMonth()],
        year : today.getFullYear()
    }
    return myTodayObj;
}

Getting Required return value from object returned by function :

var todayDate = myTodayDate().myDate;
var todayDay = myTodayDate().myDay;
var todayMonth = myTodayDate().myMonth;
var todayYear = myTodayDate().year;

The whole point of answering this question is to share this approach of getting Date in good format. Hope it helped you :)

Answer 18

I am nothing adding new here but another alternate way.

 var newCodes = function() {
     var dCodes = fg.codecsCodes.rs;
     var dCodes2 = fg.codecsCodes2.rs;
     let [...val] = [dCodes,dCodes2];
     return [...val];
 };

Answer 19

Well we can not exactly do what your trying. But something likely to below can be done.

function multiReturnValues(){
    return {x:10,y:20};
}

Then when calling the method

const {x,y} = multiReturnValues();

console.log(x) ---> 10
console.log(y) ---> 20

Answer 20

It is possible to return a string with many values and variables using the template literals `${}`

like:

var newCodes = function() {  
    var dCodes = fg.codecsCodes.rs;
    var dCodes2 = fg.codecsCodes2.rs;
    return `${dCodes}, ${dCodes2}`;
};

It's short and simple.