What should I do if the document in js is not available?

Handling Document unavailability in JavaScript: Check whether the document object exists. Use lazy loading to load scripts after the page has finished loading. Use the DOMContentLoaded event to execute code when the HTML document has finished loading. Use the document.ready method (jQuery) to execute code after the DOM has finished loading. Use window.setInterval() to create an interval loop until the document object is available.

Handling Document Unavailability in JavaScript

Problem:In JavaScript , what if the document object is not available?

Answer:

First, confirm whether the document object is indeed unavailable

Use the following code to check whether the document object exists:

<code class="javascript">if (typeof document === "undefined") {
  console.log("Document 对象不可用");
}</code>

Possible solutions

1. Use lazy loading

Load the script after the page has finished loading. This ensures that the document object is available when the script is executed.

<code class="javascript">window.onload = function() {
  // 在这里编写需要使用 document 对象的代码
};</code>

2. Use DOMContentLoaded event

This event is triggered when the HTML document is loaded, but the style sheet and other resources have not yet been loaded.

<code class="javascript">document.addEventListener("DOMContentLoaded", function() {
  // 在这里编写需要使用 document 对象的代码
});</code>

3. Use the document.ready method (jQuery)

jQuery provides a document.ready() method, which executes the provided function after the DOM is loaded. .

<code class="javascript">$(document).ready(function() {
  // 在这里编写需要使用 document 对象的代码
});</code>

4. Using window.setInterval()

You can use window.setInterval() to create an interval loop until the document object is available.

<code class="javascript">var intervalID = window.setInterval(function() {
  if (typeof document !== "undefined") {
    window.clearInterval(intervalID);

    // 在这里编写需要使用 document 对象的代码
  }
}, 50);</code>

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