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

Minimize, Copy and Paste in JavaScript

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The browser permits JavaScript scripts to learn and write to the clipboard, and mechanically copy or paste content material. On the whole, scripts shouldn’t modify the consumer’s clipboard, in order to not meet the consumer’s expectations. Nonetheless, typically it may be handy to do that, such because the “one-click copy” operate, the consumer clicks a button, and the required content material is mechanically 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 varied 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. Word that the copy operation is greatest positioned within the occasion listener operate, triggered by the consumer (for instance, the consumer clicks a button). If the script is executed autonomously, some browsers might report an error. Minimize operation can be much 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 could actually 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 may even pop up a immediate field and ask the consumer for permission. At the moment, the web page will develop into unresponsive earlier than the consumer makes a alternative. As a way 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 affordable than the standard Doc.execCommand() methodology. All its operations are asynchronous and return Promise objects with out inflicting web page jams. Furthermore, it could actually put arbitrary content material (corresponding to photos) into the clipboard. The navigator.clipboard property returns the Clipboard object, and all operations are carried out by means of this object.

const clipboardObj = navigator.clipboard;

If the navigator.clipboard property returns undefined, it implies that the present browser doesn’t assist this API (you’ll be able to see the complete compatibly desk on Can I take advantage of…). Since customers might put delicate knowledge (corresponding to passwords) on the clipboard, permitting scripts to learn them arbitrarily will trigger safety dangers, so this API has extra safety restrictions. To start with, the Chrome browser stipulates that solely HTTPS protocol pages can use this API. Nonetheless, the event setting (localhost) permits the usage of non-encrypted protocols. Secondly, the consumer’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 mechanically granted to the script, and the “learn permission” should be explicitly granted by the consumer. In different phrases, the script may be mechanically accomplished when writing to the clipboard, however when studying the clipboard, the browser will pop up a dialog field asking whether or not the consumer agrees to learn.

The permission immediate for the Clipboard API.

As well as, it ought 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 for those who 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 presently is the window of the developer software, not an online web page.

When you paste the above code into the developer software and run it, an error might be reported. As a result of when the code is operating, the developer software window is the present web page, and there’s no DOM interface that the Clipboard API is dependent upon this web page. One answer is to place the related code in setTimeout() to delay operating, 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 might 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 consumer clicks on the web page, the textual content within the clipboard might be output. Word that the browser will pop up a dialog field presently, asking the consumer whether or not to agree with the script to learn the clipboard.

If the consumer disagrees, the script will report an error. At the moment, you should utilize 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 (corresponding to photos). This methodology requires express permission from the consumer. This methodology returns a Promise object. As soon as the state of the item 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.varieties property and a clipboardItem.getType() methodology. The clipboardItem.varieties property returns an array whose members are the MIME varieties obtainable 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 varieties (textual content/html and textual content/plain). The clipboardItem.getType(sort) methodology is used to learn the information of the clip merchandise and returns a Promise object. This methodology accepts the MIME sort of the clip merchandise as a parameter and returns the information of that sort. This parameter is required, in any other case, an error might 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 consumer clicks on the net web page, the script writes textual content knowledge to the clipboard. This methodology doesn’t require consumer permission, however it’s best to place it in strive...catch to forestall 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. Word that the Chrome browser at present (till this author writes this text) solely helps writing photos in PNG format. clipboardItem() is a constructor natively supplied by the browser to generate an occasion of clipboardItem. It accepts an object as a parameter. The important thing title of the item is the MIME sort 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 consumer places knowledge into the clipboard, the copy occasion might be triggered. The next instance is to transform the textual content that the consumer places on the clipboard to uppercase.

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

  • Occasion.clipboardData.setData(sort, knowledge) : To switch the clipboard knowledge, that you must specify the information sort.
  • Occasion.clipboardData.getData(sort) : To acquire clipboard knowledge, that you must specify the information sort.
  • Occasion.clipboardData.clearData([type]) : Clear clipboard knowledge, you’ll be able to specify the information sort. If you don’t specify the sort, all sorts of knowledge might be cleared.
  • Occasion.clipboardData.objects : An array-like object accommodates all clip objects, however normally there is just one clip merchandise

The next instance is to intercept the consumer’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 consumer performs a chopping operation. Its processing is strictly the identical because the copy occasion, and the reduce knowledge can be obtained from the Occasion.clipboardData property.

When the consumer makes use of the clipboard knowledge to stick, the paste occasion might 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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