Quick tip: XMLHttpRequest and innerHTML

Quick tips for XMLHttpRequest and innerHTML

XMLHttpRequest is one of the best tips for modern DHTML. If you have never encountered it before, it is a way to issue HTTP calls to a hosted web server without refreshing the entire page—an enhanced remote script. It was originally an extension of Microsoft and has been adopted by the Mozilla browser series and (starting with version 1.2) Safari. The Sarissa library discussed earlier provides an abstraction layer for different browsers, or for a lighter approach, this code from jibbering.com (which is compiled using IE's JScript conditional) works perfectly.

Getting the most out of XMLHttpRequest often involves using server-side generated XML that your JavaScript application can retrieve, parse, and use in more complex logic. However, for a quick fix, the following code will load the HTML snippet from the URL and insert it directly into the page:

function loadFragmentInToElement(fragment_url, element_id) {
    var element = document.getElementById(element_id);
    element.innerHTML = '<p><em>Loading ...</em></p>';
    xmlhttp.open("GET", fragment_url);
    xmlhttp.onreadystatechange = function() {
        if (xmlhttp.readyState == 4 && xmlhttp.status == 200) {
            element.innerHTML = xmlhttp.responseText;
        }
    }
    xmlhttp.send(null);
}

Calculating the above function using the URL of the HTML fragment to be inserted and the ID of the element that should display the fragment. It relies on the jibbering.com code to set the xmlhttp variable.

It's absolutely fast and humble, but it's also a great quick demo of the XMLHttpRequest extension.

XMLHttpRequest and innerHTML FAQ (FAQ)

What is the difference between innerHTML and outerHTML?

innerHTML and outerHTML are both attributes of elements in the Document Object Model (DOM). The main difference between them is what they return and modify. innerHTML gets or sets the HTML content (internal HTML) of an element, while outerHTML gets or sets the HTML content, including the external wrapper of the element. In other words, innerHTML handles the content inside an element, while outerHTML handles the entire element, including the tags.

Is it safe to use innerHTML?

While innerHTML is a convenient way to inject HTML into a web page, it can pose security risks if used improperly. If you insert user-generated content into a page and use innerHTML, you may face cross-site scripting (XSS) attacks where malicious scripts are injected into your web page. To avoid this, always clean user-generated content or use a safer method such as textContent or createElement.

How to add multiple elements using innerHTML?

You can add multiple elements using innerHTML by concatenating HTML strings for each element. For example, if you want to add two paragraphs, you can do the following: element.innerHTML = '<code>element.innerHTML = '<p>第一段。</p>' '<p>第二段。</p>';First paragraph.

' '

Second paragraph.

'; This adds two paragraphs to the element.

Can I insert an SVG element using innerHTML? Yes, you can insert SVG elements using innerHTML. However, there are some things to note. The SVG namespace is not preserved when using innerHTML, which can cause problems in some browsers. If you have problems, consider using the createElementNS and appendChild methods instead.

Why does my innerHTML not work?

Your innerHTML may not work for several reasons. A common reason is that the element you are trying to modify does not exist when the script is running. This can happen if your script is loaded before the body of the page. To resolve this issue, you can move the script to the bottom of the body label, or wrap the code in the window.onload function.

Can I use innerHTML in my XML document?

No, innerHTML does not support XML documents. It is a property of the HTMLElement interface in HTML DOM and is not available in XML DOM. If you use XML, you need to use methods like createElement and appendChild instead.

How to delete all child elements of a node?

You can delete all child elements of a node by setting the innerHTML property to an empty string. For example: element.innerHTML = ''; This will delete all child elements of the element.

Can I insert text into text nodes using innerHTML?

No, innerHTML can only be used with element nodes. If you want to insert text into a text node, you should use the nodeValue or textContent property instead.

How to replace elements with innerHTML?

You can replace elements with innerHTML by setting the innerHTML property of the parent element. This will replace all child elements of the parent element, including the one you want to locate. For example: parentElement.innerHTML = '<code>parentElement.innerHTML = '<p>新段落。</p>';New paragraph.

'; This will replace all child elements of parentElement with the new paragraph.

Can I use innerHTML in Internet Explorer?

Yes, innerHTML is supported in all major browsers, including Internet Explorer. However, browsers handle certain aspects of innerHTML differently, so it is best to test your code in multiple browsers.

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