Question

这是我的代码，我不确定我是否使用了正确的循环，但这基本上是想做的。我正在尝试让数组中的每个src每隔一秒打印一次，但是当试图打印myPix数组中的第二项时，myPix [thisPic]变得未定义。我真的很乐意得到一些帮助。谢谢！

function nextPic() {
    count = -1;
    thisPic = 0;

    if (thisPic == count) {
        document.write("This shouldn't ever happen");
        return false;
    } else {
        count++;
        var myPix = new Array("images/slideshow/Jellyfish.jpg", "images/slideshow/Penguins.jpg", "images/slideshow/Lighthouse.jpg");
        slideTag = document.getElementsByTagName("img")[1];
        slideTag.src = myPix[thisPic];
        currPic = slideTag.src;
        document.write(myPix[thisPic] + "<br />");
        document.write(currPic);
    }

    return false;
}
setInterval(nextPic, 1000);

Answer 1

根据您的代码理解，我已经找到了您的问题

    var myPix = ["images/slideshow/Jellyfish.jpg", "images/slideshow/Penguins.jpg", "images/slideshow/Lighthouse.jpg"];
    counter=0;
interval = setInterval (nextPic, 1000);
    function nextPic(){
        if(counter >= myPix.length){
            document.write("This shouldn't ever happen");
            clearInterval(interval);
        }
        else{

            slideTag = document.getElementsByTagName("img")[1];
            slideTag.src = myPix[counter];
            currPic = slideTag.src;
            document.write(myPix[thisPic] + "<br />");
            document.write(currPic);
            counter++;
        }

    }

Answer 2

代码不起作用，因为＆＃34;循环＆＃34;没有共享变量。每次迭代都应该在同一个数组和相同的迭代器上工作，在你的代码中，每次迭代都会创建新的数组和新的迭代器，所以每次迭代都做同样的事情。

要正确工作，每个循环迭代都必须：

从数组获取当前图像src（在循环外部声明一个变量）
将其设置为img元素
将当前变量更改为当前+ 1（当前变量延迟外循环）

如果我们当前的数据大小超过数组大小 - 结束（ clearInterval ）或将当前设置为0 - 那么将一次又一次地启动...

＆＃13;

Time.parse('01/01/2015 3:00pm')

＆＃13;

//array declaration should be outside of loop

var myPix = new Array("https://www.gravatar.com/avatar/50fbdd1dcbe4763a33a0e212f6a632c8?s=32&d=identicon&r=PG&f=1", "https://www.gravatar.com/avatar/5be6299fb284071a9fd2cc2cc0b9090a?s=32&d=identicon&r=PG", "https://i.stack.imgur.com/mlB9c.jpg?s=48&g=1");

var currentPic=0; //this is number of current picture

function nextPic(){
          
        if (currentPic>= myPix.length){
          
          // here example how to stop:
          //clearInterval(interval);
          //return;
          
          //we loop it over again from begging
          currentPic=0;

        }
  
        //get img in page - image by currentPic
        slideTag = document.getElementsByTagName("img")[1];//second
        //set src on this slideTag from array
        slideTag.src = myPix[currentPic];
  
        currentPic++;

        
}

var interval=setInterval (nextPic, 1000);//save interval in variable to use it to stop

＆＃13;

我从stackoverflow中获取示例头像以显示工作示例：）

了解Java Script中的循环

2 个答案: