Question

此代码中的字符串是什么意思，它是交通灯脚本的一部分，我不知道每条线路的作用。

var index = 0;
var variableLen = variable.length;

function nextvariableClick() {
    index++;

    if (index == variableLen) 
        index = 0;

    var image = document.getElementById('starting_light');
    image.src = variable[index];

Answer 1

variable似乎是一个存储图像引用（URI或路径）的数组，它被提供给图像元素的src属性<img>。简单的脚本执行以下逻辑：

触发该功能时，它会将index增加1
如果index等于图像数量，则将其返回0（基本上＆＃34;循环＆＃34;通过数组
您可以通过索引variable

index

智能猜测是这是一个图像循环功能。调用nextvariableClick后，它会按照它们在variable数组中的显示顺序循环显示图像列表。

由于脚本非常简单，因此查看其功能的最佳方法是构建功能代码段：

＆＃13;

// Define dummy image references
var variable = [
  'https://placehold.it/500x300/e41a1c/ffffff',
  'https://placehold.it/500x300/377eb8/ffffff',
  'https://placehold.it/500x300/4daf4a/ffffff',
  'https://placehold.it/500x300/984ea3/ffffff',
  'https://placehold.it/500x300/ff7f00/ffffff'
];

/* Start of code you have provided */
var index = 0;
var variableLen = variable.length;

function nextvariableClick() {
  index++;

  if (index == variableLen)
    index = 0;

  var image = document.getElementById('starting_light');
  image.src = variable[index];

}
/* End of code you have provided */

// We execute the function to start initialise it, and set a starting image
nextvariableClick();
window.setInterval(nextvariableClick, 1000);

＆＃13;

<p>The function is called at runtime, and called every 1s. You should see cycling of image sources.</p>
<img id="starting_light" src="" />

＆＃13;

有人可以向我解释这段代码

1 个答案: