HomeSoftware EngineeringDiscover Clipboard Operation in JavaScript | by Sabesan Sathananthan | Geek Tradition

Discover Clipboard Operation in JavaScript | by Sabesan Sathananthan | Geek Tradition

Minimize, Copy and Paste in JavaScript

Picture by Alex Inexperienced from Pexels

The browser permits JavaScript scripts to learn and write to the clipboard, and routinely copy or paste content material. Generally, scripts shouldn’t modify the person’s clipboard, in order to not meet the person’s expectations. Nonetheless, generally it may be handy to do that, such because the “one-click copy” operate, the person clicks a button, and the required content material is routinely entered into the clipboard. At the moment, there are 3 ways to implement clipboard operations.

  • Doc.execCommand()methodology
  • Asynchronous Clipboard API
  • copy,reduce and paste Occasions

This text introduces these three strategies one after the other. That is my thirty seventh Medium article.

Doc.execCommand() is the standard methodology of manipulating the clipboard, which is supported by numerous browsers. It helps the three operations of copy, reduce, and paste.

  • Doc.execCommand('copy') — copy
  • Doc.execCommand('reduce') — reduce
  • Doc.execCommand('paste') — paste

Copy or Minimize operation

When copying, first choose the textual content after which name the Doc.execCommand('copy'), the chosen textual content will enter the clipboard.

Within the above instance, the script first selects the textual content within the inputElement of the enter field ( inputElement.choose() ), after which Doc.execCommand('copy') copies it to the clipboard. Observe that the copy operation is finest positioned within the occasion listener operate, triggered by the person (for instance, the person clicks a button). If the script is executed autonomously, some browsers might report an error. Minimize operation can be just like the copy operation.

Paste operation

When pasting, calling Doc.execCommand('paste') will output the contents of the clipboard to the present focus aspect.


Though the Doc.execCommand() methodology is handy, it has some disadvantages. First, it may possibly solely copy the chosen content material to the clipboard, and can’t write content material to the clipboard arbitrarily. Secondly, it’s an asynchronous operation. When you copy/paste a considerable amount of knowledge, the web page will freeze. Some browsers can even pop up a immediate field and ask the person for permission. Right now, the web page will change into unresponsive earlier than the person makes a selection. With a purpose to clear up these issues, browser distributors have proposed an asynchronous Clipboard API.

Clipboard API is the next-generation clipboard operation methodology, which is extra highly effective and cheap than the standard Doc.execCommand() methodology. All its operations are asynchronous and return Promise objects with out inflicting web page jams. Furthermore, it may possibly put arbitrary content material (comparable to photos) into the clipboard. The navigator.clipboard property returns the Clipboard object, and all operations are carried out by this object.

const clipboardObj = navigator.clipboard;

If the navigator.clipboard property returns undefined, it signifies that the present browser doesn’t assist this API (you may see the complete compatibly desk on Can I take advantage of…). Since customers might put delicate knowledge (comparable to passwords) on the clipboard, permitting scripts to learn them arbitrarily will trigger safety dangers, so this API has extra safety restrictions. To begin with, the Chrome browser stipulates that solely HTTPS protocol pages can use this API. Nonetheless, the event setting (localhost) permits using non-encrypted protocols. Secondly, the person’s permission must be clearly obtained when calling. The particular implementation of permissions makes use of the Permissions API. There are two permissions associated to the clipboard: clipboard-write (write permission) and clipboard-read (learn permission). The “write permission” is routinely granted to the script, and the “learn permission” should be explicitly granted by the person. In different phrases, the script may be routinely accomplished when writing to the clipboard, however when studying the clipboard, the browser will pop up a dialog field asking whether or not the person agrees to learn.

The permission immediate for the Clipboard API.

As well as, it needs to be famous that what the script reads is all the time the clipboard of the present web page. One drawback that this brings is that when you paste the related code into the developer software and run it instantly, an error could also be reported as a result of the present web page at the moment is the window of the developer software, not an internet web page.

When you paste the above code into the developer software and run it, an error shall be reported. As a result of when the code is working, the developer software window is the present web page, and there’s no DOM interface that the Clipboard API depends upon this web page. One answer is to place the related code in setTimeout() to delay working, and shortly click on on the web page window of the browser earlier than calling the operate to show it into the present web page.

After the above code is pasted into the developer software to run, shortly click on on the web page window of the webpage to make it the present web page, in order that no error shall be reported.

Clipboard object


The clipboard.readText() methodology is used to repeat the textual content knowledge within the clipboard.

Within the above instance, after the person clicks on the web page, the textual content within the clipboard shall be output. Observe that the browser will pop up a dialog field at the moment, asking the person whether or not to agree with the script to learn the clipboard.

If the person disagrees, the script will report an error. Right now, you need to use the strive...catch construction to deal with errors.


The clipboard.learn() methodology is used to repeat the information within the clipboard, which may be textual content knowledge or binary knowledge (comparable to photos). This methodology requires specific permission from the person. This methodology returns a Promise object. As soon as the state of the thing turns into resolved, an array may be obtained, and every array member is an occasion of a ClipboardItem object.

The ClipboardItem object represents a single clip merchandise and every clip merchandise has a clipboardItem.sorts property and a clipboardItem.getType() methodology. The clipboardItem.sorts property returns an array whose members are the MIME sorts accessible for the clip merchandise. For instance, a clip merchandise may be pasted in HTML format or in plain textual content format. Then it has two MIME sorts (textual content/html and textual content/plain). The clipboardItem.getType(kind) methodology is used to learn the information of the clip merchandise and returns a Promise object. This methodology accepts the MIME kind of the clip merchandise as a parameter and returns the information of that kind. This parameter is required, in any other case, an error shall be reported.


The clipboard.writeText() methodology is used to put in writing textual content content material to the clipboard.

The above instance is that after the person clicks on the internet web page, the script writes textual content knowledge to the clipboard. This methodology doesn’t require person permission, however it’s best to place it in strive...catch to stop errors.


The clipboard.write() methodology is used to put in writing arbitrary knowledge to the clipboard, which may be textual content knowledge or binary knowledge. This methodology accepts a ClipboardItem occasion as a parameter, which represents the information written to the clipboard.

Within the above instance, the script writes an image to the clipboard. Observe that the Chrome browser presently (till this author writes this text) solely helps writing pictures in PNG format. clipboardItem() is a constructor natively offered by the browser to generate an occasion of clipboardItem. It accepts an object as a parameter. The important thing identify of the thing is the MIME kind of the information, and the important thing worth is the information itself. The next instance is to put in writing the worth of the identical clip merchandise in a number of codecs to the clipboard, one is textual content knowledge, and the opposite is binary knowledge for pasting on totally different events.

When the person places knowledge into the clipboard, the copy occasion shall be triggered. The next instance is to transform the textual content that the person places on the clipboard to uppercase.

Within the above instance, the clipboardData property of the occasion object incorporates the clipboard knowledge. It’s an object with the next properties and strategies.

  • Occasion.clipboardData.setData(kind, knowledge) : To change the clipboard knowledge, that you must specify the information kind.
  • Occasion.clipboardData.getData(kind) : To acquire clipboard knowledge, that you must specify the information kind.
  • Occasion.clipboardData.clearData([type]) : Clear clipboard knowledge, you may specify the information kind. If you don’t specify the kind, all kinds of knowledge shall be cleared.
  • Occasion.clipboardData.gadgets : An array-like object incorporates all clip gadgets, however often there is just one clip merchandise

The next instance is to intercept the person’s copy operation and put the required content material into the clipboard.

Within the above instance, first, use e.preventDefault() to cancel the default operation of the clipboard, after which the script takes over the copy operation. The reduce occasion is triggered when the person performs a slicing operation. Its processing is precisely the identical because the copy occasion, and the reduce knowledge can be obtained from the Occasion.clipboardData property.

When the person makes use of the clipboard knowledge to stick, the paste occasion shall be triggered. The next instance is to intercept the paste operation, the information within the clipboard is taken out by the script.



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