Uncaught TypeError: Cannot set property ‘onmouseover‘ of undefined（数组越界问题）

我就是我 2022-09-12 13:47 125阅读 0赞

如果调用函数的过程中数组越界就会报错。

<!DOCTYPE html>
    <html lang="en">
      <head>
        <meta charset="UTF-8" />
        <meta http-equiv="X-UA-Compatible" content="IE=edge" />
        <meta name="viewport" content="width=device-width, initial-scale=1.0" />
        <title>Document</title>
        <script>
          window.onload = function () {
            for (i = 0; i < 10; i++) {
              console.log(i);
            }
            name1 = document.getElementsByTagName("li");
            console.log(name1.length);
            for (var num = 0; num < name1.length; num++) {
              console.log(num);
              name1[num].style.color = "red";
            }
            console.log(i);
            say(5);
          };
          function say(num) {
            console.log("111");
            if (num == 5) {
              console.log("1111");
              //你kin你擦，for循环的执行顺序都忘记了，害自己找了半天 执行完成里面的再i++再比较，所以最后j还是可以为3,但是为3的时候不会执行里面的内容。
              for (var j = 0; j < 3; j++) {
                // alert("nihao");
                console.log(j);
              }
              name1[3].onmouseover = function () {
                console.log(this.innerHTML);
              };
            }
            console.log("hhhh");
            console.log(name1[0]);
            console.log(name1[1]);
            console.log(name1[2]);
            console.log(name1[3]);
            console.log(name1[7]);
          }
        </script>
      </head>
      <body>
        <ul>
          <li>ni</li>
          <li>hao</li>
          <li>shi</li>
          <li>jie</li>
        </ul>
      </body>
    </html>

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