Javascript getelementbyid innerhtml value

JavaScript HTML DOM — Changing HTML

The HTML DOM allows JavaScript to change the content of HTML elements.

Changing HTML Content

The easiest way to modify the content of an HTML element is by using the innerHTML property.

To change the content of an HTML element, use this syntax:

This example changes the content of a

element:

Example

• The HTML document above contains a

  element with id=»p1″

• We use the HTML DOM to get the element with id=»p1″
• A JavaScript changes the content ( innerHTML ) of that element to «New text!»

This example changes the content of an element:

Example

• The HTML document above contains an element with id=»id01″
• We use the HTML DOM to get the element with id=»id01″
• A JavaScript changes the content ( innerHTML ) of that element to «New Heading»

Changing the Value of an Attribute

To change the value of an HTML attribute, use this syntax:

This example changes the value of the src attribute of an element:

Example

• The HTML document above contains an element with id=»myImage»
• We use the HTML DOM to get the element with id=»myImage»
• A JavaScript changes the src attribute of that element from «smiley.gif» to «landscape.jpg»

Dynamic HTML content

JavaScript can create dynamic HTML content:

Example

document.write()

In JavaScript, document.write() can be used to write directly to the HTML output stream:

Example

Never use document.write() after the document is loaded. It will overwrite the document.

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Element: innerHTML property

The Element property innerHTML gets or sets the HTML or XML markup contained within the element.

To insert the HTML into the document rather than replace the contents of an element, use the method insertAdjacentHTML() .

Value

A string containing the HTML serialization of the element’s descendants. Setting the value of innerHTML removes all of the element’s descendants and replaces them with nodes constructed by parsing the HTML given in the string htmlString.

Exceptions

Thrown if an attempt was made to set the value of innerHTML using a string which is not properly-formed HTML.

Thrown if an attempt was made to insert the HTML into a node whose parent is a Document .

Usage notes

The innerHTML property can be used to examine the current HTML source of the page, including any changes that have been made since the page was initially loaded.

Reading the HTML contents of an element

Reading innerHTML causes the user agent to serialize the HTML or XML fragment comprised of the element’s descendants. The resulting string is returned.

let contents = myElement.innerHTML; 

This lets you look at the HTML markup of the element’s content nodes.

Note: The returned HTML or XML fragment is generated based on the current contents of the element, so the markup and formatting of the returned fragment is likely not to match the original page markup.

Replacing the contents of an element

Setting the value of innerHTML lets you easily replace the existing contents of an element with new content.

Note: This is a security risk if the string to be inserted might contain potentially malicious content. When inserting user-supplied data you should always consider using Element.setHTML() instead, in order to sanitize the content before it is inserted.

For example, you can erase the entire contents of a document by clearing the contents of the document’s body attribute:

This example fetches the document’s current HTML markup and replaces the »

.documentElement.innerHTML = ` $document.documentElement.innerHTML.replace( //g, "<", )> `; 

Operational details

What exactly happens when you set value of innerHTML ? Doing so causes the user agent to follow these steps:

1. The specified value is parsed as HTML or XML (based on the document type), resulting in a DocumentFragment object representing the new set of DOM nodes for the new elements.
2. If the element whose contents are being replaced is a element, then the element’s content attribute is replaced with the new DocumentFragment created in step 1.
3. For all other elements, the element’s contents are replaced with the nodes in the new DocumentFragment .

Appending HTML to an element

Setting the value of innerHTML lets you append new contents to the existing one of an element.

HTML

ul id="list"> li>a href="#">Item 1a>li> li>a href="#">Item 2a>li> li>a href="#">Item 3a>li> ul> 

JavaScript

Please note that using innerHTML to append HTML elements (e.g. el.innerHTML += «link» ) will result in the removal of any previously set event listeners. That is, after you append any HTML element that way you won’t be able to listen to the previously set event listeners.

Security considerations

It is not uncommon to see innerHTML used to insert text into a web page. There is potential for this to become an attack vector on a site, creating a potential security risk.

let name = "John"; // assuming 'el' is an HTML DOM element el.innerHTML = name; // harmless in this case // … name = ""; el.innerHTML = name; // harmless in this case 

Although this may look like a cross-site scripting attack, the result is harmless. HTML specifies that a tag inserted with innerHTML should not execute.

const name = ""; el.innerHTML = name; // shows the alert 

For that reason, it is recommended that instead of innerHTML you use:

• Element.setHTML() to sanitize the text before it is inserted into the DOM.
• Node.textContent when inserting plain text, as this inserts it as raw text rather than parsing it as HTML.

Warning: If your project is one that will undergo any form of security review, using innerHTML most likely will result in your code being rejected. For example, if you use innerHTML in a browser extension and submit the extension to addons.mozilla.org, it may be rejected in the review process. Please see Safely inserting external content into a page for alternative methods.

Examples

This example uses innerHTML to create a mechanism for logging messages into a box on a web page.

JavaScript

function log(msg)  const logElem = document.querySelector(".log"); const time = new Date(); const timeStr = time.toLocaleTimeString(); logElem.innerHTML += `$timeStr>: $msg>
`; > log("Logging mouse events inside this container…"); 

The log() function creates the log output by getting the current time from a Date object using toLocaleTimeString() , and building a string with the timestamp and the message text. Then the message is appended to the box with the class «log» .

We add a second method that logs information about MouseEvent based events (such as mousedown , click , and mouseenter ):

function logEvent(event)  const msg = `Event $event.type> at $event.clientX>, $event.clientY> `; log(msg); > 

Then we use this as the event handler for a number of mouse events on the box that contains our log:

const boxElem = document.querySelector(".box"); boxElem.addEventListener("mousedown", logEvent); boxElem.addEventListener("mouseup", logEvent); boxElem.addEventListener("click", logEvent); boxElem.addEventListener("mouseenter", logEvent); boxElem.addEventListener("mouseleave", logEvent); 

HTML

The HTML is quite simple for our example.

div class="box"> div>strong>Log:strong>div> div class="log">div> div> 

CSS

The following CSS styles our example content.

.box  width: 600px; height: 300px; border: 1px solid black; padding: 2px 4px; overflow-y: scroll; overflow-x: auto; > .log  margin-top: 8px; font-family: monospace; > 

Result

The resulting content looks like this. You can see output into the log by moving the mouse in and out of the box, clicking in it, and so forth.

Specifications

Browser compatibility

BCD tables only load in the browser

See also

• Node.textContent and HTMLElement.innerText
• Element.insertAdjacentHTML()
• Element.outerHTML
• Element.setHTML
• Parsing HTML or XML into a DOM tree: DOMParser
• Serializing a DOM tree into an XML string: XMLSerializer

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HTML DOM Element innerHTML

The innerHTML property sets or returns the HTML content (inner HTML) of an element.

See Also:

The Differences Between
innerHTML, innerText and textContent

Syntax

Return the innerHTML property:

Set the innerHTML property:

Property Value

Return Value

More Examples

Example

Change the HTML content of two elements:

let text = «Hello Dolly.»;
document.getElementById(«myP»).innerHTML = text;
document.getElementById(«myDIV»).innerHTML = text;

Example

Repeat the HTML content of an element:

Example

Change the HTML content and URL of a link:

The Differences Between
innerHTML, innerText and textContent

The innerHTML property returns: The text content of the element, including all spacing and inner HTML tags.

The innerText property returns: Just the text content of the element and all its children, without CSS hidden text spacing and tags, except and elements.

The textContent property returns: The text content of the element and all descendaces, with spacing and CSS hidden text, but without tags.

HTML Example

JavaScript Examples

let text = document.getElementById(«myP»).innerText;

let text = document.getElementById(«myP»).innerHTML;

let text = document.getElementById(«demo»).textContent;

The innerText property returns: This element has extra spacing and contains a span element.

The innerHTML property returns: This element has extra spacing and contains a span element.

The textContent property returns: This element has extra spacing and contains a span element.

Browser Support

element.innerHTML is supported in all browsers:

Chrome	Edge	Firefox	Safari	Opera	IE
Yes	Yes	Yes	Yes	Yes	Yes

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Свойство innerHTML

Дополнительные примеры «Попробуй сам» приведены ниже.

Определение и использование

Свойство innerHTML задает или возвращает HTML-содержимое (innerHTML) элемента.

Поддержка браузера

Синтаксис

Возвращает свойство innerHTML:

Установит свойство innerHTML:

Свойство значений

Технические детали

Ещё примеры

Пример

Получите HTML-содержимое элемента

с помощью >

Пример

Пример

Измените HTML-содержимое двух элементов:

document.getElementById(«myP»).innerHTML = «Привет Андрей.»;
document.getElementById(«myDIV»).innerHTML = «Как ты??»;

Пример

Оповещать HTML-содержимое элемента

с помощью >

Пример

Удалите HTML-содержимое элемента

с помощью >

document.getElementById(«demo»).innerHTML = «»; // Заменяет содержимое

пустой строкой

Пример

Измените HTML-содержимое, URL-адрес и цель ссылки:

document.getElementById(«myAnchor»).innerHTML = «Schoolsw3»;
document.getElementById(«myAnchor»).href = «https://www.schoolsw3.com»;
document.getElementById(«myAnchor»).target = «_blank»;

Упражнения

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