javascript - 存储带间隔的随机数组值

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我该如何用白色/无背景替换旧的“盒子”？

var counter = 11;
var check = 0;
var boxes = ["box_1","box_2","box_3","box_4"];

clock = setInterval(function() {
    counter--;
    if(counter==0) {
        clearInterval(clock);
        document.getElementById("counter").innerHTML="Time Left: 0 seconds.";
    } else {
        var box = boxes[Math.floor(Math.random()*boxes.length)];
        document.getElementById("counter").innerHTML="Time Left: " + counter.toString() + " seconds.";
        document.getElementById(box).style.backgroundColor="#000";
    }
}, 1000);

我尝试将盒子存储为 old_box -> old_box = box这不起作用。

看来人们有误解。我想存储框值，以便我可以在下一个循环中回调它并将其设置为白色，而新框可以设置为黑色。

Answer 1

您需要记住该框:

var counter = 11;
var check = 0;
var boxes = ["box_1","box_2","box_3","box_4"];
var lastbox = false;
clock = setInterval(function() {
counter--;
if(counter==0) {
    clearInterval(clock);
    document.getElementById("counter").innerHTML="Time Left: 0 seconds.";
} else {
    if (lastbox) {
        document.getElementById(lastbox).style.backgroundColor = "#FFF";
    }
    lastbox = boxes[Math.floor(Math.random()*boxes.length)];
    document.getElementById("counter").innerHTML="Time Left: " + counter.toString() + " seconds.";
    document.getElementById(lastbox).style.backgroundColor="#000";
}
}, 1000);