选择随机数组，然后从该数组中选择一个元素

Question

I'm trying to figure out if it's possible to first choose a random array (on load) and then an element from this chosen array. So for example I have:

    var colorsOne = ["#CCCCCC","#333333","#990099","#990099"];  
    var colorsTwo = ["#CCCCCC","#333333","#990099","#990099"];  
    var colorsThree = ["#CCCCCC","#333333","#990099","#990099"];  
    var colorsFour = ["#CCCCCC","#333333","#990099","#990099"];  
    var colorsFive = ["#CCCCCC","#333333","#990099","#990099"];  
    var colorsSix = ["#CCCCCC","#333333","#990099","#990099"];  
    var colorsSeven = ["#CCCCCC","#333333","#990099","#990099"];  
    var colorsEight = ["#CCCCCC","#333333","#990099","#990099"];  
    var colorsNine = ["#CCCCCC","#333333","#990099","#990099"];  
    var colorsTen = ["#CCCCCC","#333333","#990099","#990099"];  
    var colorsEleven = ["#CCCCCC","#333333","#990099","#990099"];  
    var colorsTwelve = ["#CCCCCC","#333333","#990099","#990099"];  

12 arrays (each one will eventually be populated with different hex codes), I first need to choose one of these array and then one hex code (at random) from this array.

eg

var rand = Math.floor(Math.random() * 4);               
$('.header-wrap').css("background-color", colorsEight[rand]);

this will take a random element from coloursEight array, but I've had to program that, I need to choose an array randomly first and THEN choose an element from this array.

Any suggestions for this would be greatly appreciated!

Answer 1

The answer is pretty much inherent in the question. :-) Put the arrays into an array, then do the same thing you're doing:

var colors = [
    ["#CCCCCC","#333333","#990099","#990099"],
    ["#CCCCCC","#333333","#990099","#990099"],
    ["#CCCCCC","#333333","#990099","#990099"],
    ["#CCCCCC","#333333","#990099","#990099"],
    ["#CCCCCC","#333333","#990099","#990099"],
    ["#CCCCCC","#333333","#990099","#990099"],
    ["#CCCCCC","#333333","#990099","#990099"],
    ["#CCCCCC","#333333","#990099","#990099"],
    ["#CCCCCC","#333333","#990099","#990099"],
    ["#CCCCCC","#333333","#990099","#990099"],
    ["#CCCCCC","#333333","#990099","#990099"],
    ["#CCCCCC","#333333","#990099","#990099"]
];

var array = colors[Math.floor(Math.random() * colors.length)];
var color = array[Math.floor(Math.random() * array.length)];
$('.header-wrap').css("background-color", color);

If for some reason you need those separate array variables, you can still gather them together:

var colorsOne = ["#CCCCCC","#333333","#990099","#990099"];  
var colorsTwo = ["#CCCCCC","#333333","#990099","#990099"];  
var colorsThree = ["#CCCCCC","#333333","#990099","#990099"];  
var colorsFour = ["#CCCCCC","#333333","#990099","#990099"];  
var colorsFive = ["#CCCCCC","#333333","#990099","#990099"];  
var colorsSix = ["#CCCCCC","#333333","#990099","#990099"];  
var colorsSeven = ["#CCCCCC","#333333","#990099","#990099"];  
var colorsEight = ["#CCCCCC","#333333","#990099","#990099"];  
var colorsNine = ["#CCCCCC","#333333","#990099","#990099"];  
var colorsTen = ["#CCCCCC","#333333","#990099","#990099"];  
var colorsEleven = ["#CCCCCC","#333333","#990099","#990099"];  
var colorsTwelve = ["#CCCCCC","#333333","#990099","#990099"]
var colors = [
    colorsOne,
    colorsTwo,
    colorsThree,
    colorsFour,
    colorsFive,
    colorsSix,
    colorsSeven,
    colorsEight,
    colorsNine,
    colorsTen,
    colorsEleven,
    colorsTwelve
];

var array = colors[Math.floor(Math.random() * colors.length)];
var color = array[Math.floor(Math.random() * array.length)];
$('.header-wrap').css("background-color", color);

Answer 2

You simply need to generate a 2-dimensional array from all your existing arrays.

var super_array = [colorsOne, colorsTwo, ...];

Then simply grab a random index for super_array and you now have a single array that you can use to your hearts desire.

var rand_x = Math.floor(Math.random() * 4); 
var rand_y = Math.floor(Math.random() * 4);              
$('.header-wrap').css("background-color", super_array[rand_x][rand_y]);

Answer 3

function randomArrVal(arr) {
 return arr[Math.floor(arr.length * Math.random())];
}
var array2D = [
  ["#CCCCCC","#333333","#990099","#990099"],
  ["#CCCCCC","#333333","#990099","#990099"],
  ["#CCCCCC","#333333","#990099","#990099"],
  ["#CCCCCC","#333333","#990099","#990099"],
  ["#CCCCCC","#333333","#990099","#990099"],
  ["#CCCCCC","#333333","#990099","#990099"],
  ["#CCCCCC","#333333","#990099","#990099"],
  ["#CCCCCC","#333333","#990099","#990099"],
  ["#CCCCCC","#333333","#990099","#990099"],
  ["#CCCCCC","#333333","#990099","#990099"],
  ["#CCCCCC","#333333","#990099","#990099"],
  ["#CCCCCC","#333333","#990099","#990099"]
];

$('.header-wrap').css("background-color", randomArrVal(randomArrVal(array2D)));

Answer 4

There seems to be no reason for creating named arrays. You could just create a Multi-Dimensional Array and get the Color you want off it. The snippet below demonstrates that....

    // BUNDLE ALL THE INDIVIDUAL ARRAY OF COLORS
    // INTO ONE SINGLE ARRAY THUS CREATING A MULTI-DIMENSIONAL ARRAY.
    var arrHexColors    = [
        ["#CCCCCC","#333333","#990099","#990099"],
        ["#CCCCCC","#333333","#990099","#990099"],
        ["#CCCCCC","#333333","#990099","#990099"],
        ["#CCCCCC","#333333","#990099","#990099"],
        ["#CCCCCC","#333333","#990099","#990099"],
        ["#CCCCCC","#333333","#990099","#990099"],
        ["#CCCCCC","#333333","#990099","#990099"],
        ["#CCCCCC","#333333","#990099","#990099"],
        ["#CCCCCC","#333333","#990099","#990099"],
        ["#CCCCCC","#333333","#990099","#990099"],
        ["#CCCCCC","#333333","#990099","#990099"],
        ["#CCCCCC","#333333","#990099","#990099"]
    ];

    // IF NECESSARY (SHOULD THE KEYS BE IMPORTANT TO YOU);
    // CREATE AN ARRAY TO HOLD THE KEYS TO THE INDIVIDUAL ARRAY...
    // THE IDEA HERE IS TO CREATE A PARALLEL ARRAY, WITH THE KEYS HERE
    // CORRESPONDING TO THE KEYS REPRESENTING ITS CONTENT IN THE MULTI-DIMENSIONAL ARRAY.
    var arrColorKeys    = [
        'colorsOne',
        'colorsTwo',
        'colorsThree',
        'colorsFour',
        'colorsFive',
        'colorsSix',
        'colorsSeven',
        'colorsEight',
        'colorsNine',
        'colorsTen',
        'colorsEleven',
        'colorsTwelve'
    ];

    // GENERATE A RANDOM NUMBER THAT SHOULD BE 
    // "ONE" LESS THAN THE LENGTH OF THE MULTI-DIMENSIONAL ARRAY
    var arrRandomColor  = arrHexColors[ Math.floor(Math.random() * arrHexColors.length) ];

    // DO THE SAME FOR THE COLOR KEYS ARRAY - IF NEEDED....
    var arrRandomKey    = arrRandomColor[ Math.floor(Math.random() * arrRandomColor.length) ];

    // USING THE GENERATED RANDOM NUMBER PICK THE ARRAY 
    // CORRESPONDING TO THAT KEY
    var randomColor     = arrRandomColor[ Math.floor(Math.random() * arrRandomColor.length) ];

    $('.header-wrap').css("background-color", randomColor);

    console.log(randomColor);