Remove an element from an array in Javascript [duplicate]

You need to use the array's splice() method. However, you're creating a new array every iteration, so you need to move that part out of the loop.

function write() {
    var questions = [
        "If you are goofy which is your leading foot",
        "Riding switch is when you do what",
        "On your toe side which way should you lean",
        "question 4",
        "question 5",
        "question 6"
    ];

    for (var x = 1; x <= 3; x++) {
        var rnd = Math.floor(questions.length * Math.random());
        document.write(questions[rnd] + "<br>");
        questions.splice(rnd, 1);
    }
}

You can try:

question.splice(rnd,1)

Put this at the end of your loop, and it will remove the element that has just been displayed.

Instead of removing an element from the array you could keep track of the random indices which you have already used and avoid them. Something like this:

function write() {
  for (var x = 1; x <= 3; x++) {
    var question = new Array(...);
    var used={}, l=question.length, rnd;
    do {
      rnd = Math.floor(l * Math.random());
    } while (rnd in used);
    used[rnd] = true;
    document.write(question[rnd]);
    document.write("<br>")
  }
}

I agree with Tim's response. In addition, though, you can compact the code a little bit more by doing it like this:

function write() {
  var question = ["If you are goofy which is your leading foot", "Riding switch is when you do what", "On your toe side which way should you lean", "question 4", "question 5", "question 6"];

  for (var x = 1; x <= 3; x++) {
    var rnd = Math.floor(question.length * Math.random());
    document.write(question.splice(rnd, 1)[0] + "<br>");
  }
}

The reason the above code will also work is because splice not only removes the element, but also returns the sub-array that was removed.