Change background colour and text colour on click

Question

What I have been trying -unsuccessfully- to achieve is to change the colour of the background and the text by clicking one <a> element, randomly rotating amongst several colour combinations.

My default colours are:

color: #1B1725;
background-color: #A30B37;

I would like to use, at least, three colour combinations more (for the sake of this example, those three other combinations can be basic colours).

Edit for further development:

I need just one button that toggles between three colour combinations (not random colours).

What I have tried so far:

    function changeColor(combo) {
  if(combo=="combo1"){
    document.body.style.backgroundColor = "#FEFAE0";
    document.body.style.color = "red";   
  }else if(combo=="combo1"){
    document.body.style.backgroundColor = "blue";
    document.body.style.color = "white";
  }  
}

Using this, it changes from the default colours to the "combo1" colours. I would need that button to keep changing on click.

Answer 1

You can generate random colors like this:

// Generate random colors
var bg = Math.floor(Math.random()*16777215).toString(16);
var text = Math.floor(Math.random()*16777215).toString(16);

OR

// To generate predefined colors
function getRandomInt(max) {
 return Math.floor(Math.random() * max);
}
var colors = ["000000","FEFEFE","FFFAAA"];
var bg = colors[getRandomInt(colors.length)];
var text = colors[getRandomInt(colors.length)];
    

Finally

var div = document.getElementById('mydiv');
var a= document.getElementById('atagid');
a.onclick = function() {
  div.style.backgroundColor = "#"+bg;
  div.style.color= "#"+text;
}

Answer 2

Here is sandbox example: https://codesandbox.io/s/currying-cherry-nt80k?file=/index.html

function getColorChange(){
    var x = 1
    var a = "black"

    var intervalID = setInterval(function () {
        document.getElementById("changeColor").style.backgroundColor = a;
        if (x == 1) {
            a = "green"
        }
        if (x == 2 ) {
            a="red"
        }
        if (++x === 4) {
            window.clearInterval(intervalID);
        }
    }, 5000);
}