通过 document.getElementById 设置 check = notnull

通过 document.getElementById 方法可以获取到指定 id 的 HTML 元素对象。要设置一个元素的属性值为 "notnull"，可以使用元素对象的属性赋值方式来实现。

以下是通过 document.getElementById 设置 check 属性为 "notnull" 的示例代码：

var element = document.getElementById("check");
element.setAttribute("check", "notnull");

在上述代码中，我们首先使用 document.getElementById 方法获取到 id 为 "check" 的元素对象，并将其赋值给变量 element。然后，使用元素对象的 setAttribute 方法来设置 check 属性的值为 "notnull"。

相关问题

Calling appendChild() on a null node does nothing.

This error occurs when you try to append a child element to a parent element that doesn't exist or is null.

To resolve this error, make sure that the parent element exists and is accessible in the current scope. You can also check if the parent element has been initialized or created before trying to append a child element to it.

Here's an example of how to create a new element and append it to an existing parent element:

// create a new div element
const newDiv = document.createElement('div');

// get the parent element by its ID
const parentElement = document.getElementById('parent');

// check if the parent element exists
if (parentElement) {
  // append the new div element to the parent element
  parentElement.appendChild(newDiv);
} else {
  console.error('Parent element not found!');
}

In this example, we first create a new `div` element using the `createElement()` method. Then, we try to get the parent element by its ID using the `getElementById()` method. If the parent element exists, we append the new `div` element to it using the `appendChild()` method. If the parent element doesn't exist, we log an error message to the console.

react-dom.development.js:4312 Uncaught TypeError: Cannot read properties of null (reading 'scrollIntoView')

This error occurs when the code is trying to access the 'scrollIntoView' property of an element that is null or undefined. This property is used to scroll the element into view when it is not visible on the screen.

To fix this error, you need to identify which element is causing the issue and make sure that it is not null or undefined before trying to access its 'scrollIntoView' property. You can use console.log statements or a debugger to identify the problematic code and then add a check to ensure that the element exists before calling the 'scrollIntoView' method.

For example, you can use the following code to check if the element exists before calling the 'scrollIntoView' method:

const element = document.getElementById('myElement');
if (element) {
  element.scrollIntoView();
}

This will prevent the error from occurring and ensure that the element is scrolled into view only if it exists.