How to get random number only once JavaScript [duplicate]

This question already has an answer here:

• How can i shuffle an array in JavaScript? [duplicate] 2 answers

Guys I have array with five strings inside. Then I have loop and inside loop I have Math.random to get 1,2,3,4 and 5 numbers. So as you guess I want to change array's each string randomly, but if I changed one of them once I want to re-random a number and change the next string. The problem is that only re-randoms once but I want it to do until it gets to unchanged string.

<button id="button" onclick="change()">me</button>
<p id="par"></p>

var holder = ["empty","empty","empty","empty","empty"];


var change = function(){
for(var i=0; i<holder.length; i++){
var rand = Math.floor((Math.random() * 5) + 1);

switch (rand) {
    case 1:
        if (holder[0] === "empty"){
            holder[0] = "ocupied"
        }else{rand = Math.floor((Math.random() * 5) + 1)}
        break;
    case 2:
        if (holder[1] === "empty"){
            holder[1] = "ocupied"
        }else{rand = Math.floor((Math.random() * 5) + 1)}
        break;
    case 3:
        if (holder[2] === "empty"){
            holder[2] = "ocupied"
        }else{rand = Math.floor((Math.random() * 5) + 1)}
        break;
    case 4:
        if (holder[3] === "empty"){
            holder[3] = "ocupied"
        }else{rand = Math.floor((Math.random() * 5) + 1)}
        break;
    case 5:
        if (holder[4] === "empty"){
            holder[4] = "ocupied"
        }else{rand = Math.floor((Math.random() * 5) + 1)}
        break;
}


    document.getElementById('par').innerHTML = holder;
};