Javascript equivalent of PHP's list()

Question

Really like that function.

$matches = array('12', 'watt');
list($value, $unit) = $matches;

Is there a Javascript equivalent of that?

Answer 1

There is, but in "new" versions of Javascript: Destructuring assignment - Javascript 1.7. It's probably only supported in Mozilla-based browsers, and maybe in Rhino.

var a = 1;  
var b = 3;  

[a, b] = [b, a];  

EDIT: actually it wouldn't surprise me if the V8 Javascript library (and thus Chrome) supports this. But don't count on it either :)

Answer 2

try this:

matches = ['12', 'watt'];
[value, unit] = matches; 

Answer 3

ES6 does support this directly now via array destructuring.

const matches = ['12', 'watt'];
const [value, unit] = matches;

Answer 4

This is my solution for using List/Explode on Javascript. Fiddle Working Example

First the implementation :

var dateMonth = "04/15";
dateMonth.split("/").list("month","day", "year");
month == "04";
day == "15";
year == null;

It also allows for scoping the new generated variables :

var scoped = (function()
{ 
    var dateMonth = "07/24/2013"; 
    dateMonth.split("/").list("month","day", "year", this);
    this.month == "07";
    this.day == "24";
    this.year == "2013";
})();

This was accomplished by modifying an the Array prototype.

Array.prototype.list = function()
{
    var 
        limit = this.length,
        orphans = arguments.length - limit,
        scope = orphans > 0  && typeof(arguments[arguments.length-1]) != "string" ? arguments[arguments.length-1] : window 
    ;

    while(limit--) scope[arguments[limit]] = this[limit];

    if(scope != window) orphans--;

    if(orphans > 0)
    {
        orphans += this.length;
        while(orphans-- > this.length) scope[arguments[orphans]] = null;  
    }  
}

Answer 5

There is a experimental implementation of list() by PHPJS here:
https://github.com/kvz/phpjs/blob/master/_experimental/array/list.js

Answer 6

CoffeeScript offers destructuring assignment with the syntax:

[a, b] = someFunctionReturningAnArray()

This is pretty much identical to the feature offered in very new JavaScript versions. However, CoffeeScript produces compiled JS that is compatible even with IE6's JavaScript engine, and therefore it's a good option if compatibility is vital.

Answer 7

Since most JavaScript implementations don't yet support that feature, you could simply do it in a more JavaScript-like fashion:

function list(){
    var args = arguments;
    return function(array){
        var obj = {};
        for(i=0; i<args.length; i++){
            obj[args[i]] = array[i];
        }
        return obj;
    };
}

Example:

var array = ['GET', '/users', 'UserController'];
var obj = {};

obj = list('method', 'route', 'controller')(array);

console.log(obj.method);        // "GET"
console.log(obj.route);         // "/users"
console.log(obj.controller);    // "UserController"

Check the fiddle

---

An alternative is to add a list-method to Array.prototype (even I wouldn't recommend it):

Array.prototype.list = function(){
    var i, obj = {};
    for(i=0; i<arguments.length; i++){
        obj[arguments[i]] = this[i];
    }
    // if you do this, you pass to the dark side `,:,´
    this.props = obj;
    return obj;
};

Example:

/**
 * Example 1: use Array.prototype.props
 */

var array = ['GET', '/users', 'UserController'];
array.list('method', 'route', 'controller');

console.log(array.props.method);        // "GET"
console.log(array.props.route);         // "/users"
console.log(array.props.controller);    // "UserController"

/**
 * Example 2: use the return value
 */

var array = ['GET', '/users', 'UserController'];
var props = array.list('method', 'route', 'controller');

console.log(props.method);      // "GET"
console.log(props.route);       // "/users"
console.log(props.controller);  // "UserController"

Check the fiddle for that one

Answer 8

This is my hack at it; as short as I could get it without writing a function to do it. Gotta be careful of the scope of "this" though:

list = ["a","b","c"];
vals = [1,2,3];
for(var i in vals)this[list[i]]=vals[i];
console.log(a,b,c);

Good enough for a laugh. I still assign each variable one at a time:

a=vals[0];
b=vals[1];
c=vals[2];

It's much shorter this way. Besides, if you've got a bunch of variables they should probably be kept in the array, or even better they should be properties of a closure, instead of declaring them all separately.

Answer 9

function list(fn,array){
    if(fn.length && array.length){
        for(var i=0;i<array.length;i++){
            var applyArray = [];
            for(var j=0;j<array[i].length;j++){
                fn[j] = array[i][j];
                applyArray.push(fn[j]);
            }
        fn.apply(this,applyArray);
       }
   }
}

Example:

//array array mixture for composure
var arrayMixture = [ ["coffee","sugar","milk"], ["tea","sugar","honey"] ];
//call our function


list(function(treat,addin,addin2){
    console.log("I like "+treat+" with " + addin + " and " + addin2);
},arrayMixture);


//output:
//I like coffee with sugar and milk
//I like tea with sugar and honey