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

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


Lower, Copy and Paste in JavaScript

Photograph by Alex Inexperienced from Pexels

The browser permits JavaScript scripts to learn and write to the clipboard, and robotically copy or paste content material. Normally, 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” perform, the consumer clicks a button, and the required content material is robotically entered into the clipboard. Presently, there are 3 ways to implement clipboard operations.

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

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

Doc.execCommand() is the normal methodology of manipulating the clipboard, which is supported by varied browsers. It helps the three operations of copy, lower, and paste.

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

Copy or Lower 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. Be aware that the copy operation is greatest positioned within the occasion listener perform, triggered by the consumer (for instance, the consumer clicks a button). If the script is executed autonomously, some browsers might report an error. Lower 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 component.

Drawback

Though the Doc.execCommand() methodology is handy, it has some disadvantages. First, it will probably 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. In case you copy/paste a considerable amount of information, the web page will freeze. Some browsers may even pop up a immediate field and ask the consumer for permission. Right now, the web page will grow to be unresponsive earlier than the consumer makes a alternative. With the intention to remedy 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 normal Doc.execCommand() methodology. All its operations are asynchronous and return Promise objects with out inflicting web page jams. Furthermore, it will probably put arbitrary content material (reminiscent of footage) 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 possibly can see the total compatibly desk on Can I take advantage of…). Since customers might put delicate information (reminiscent of passwords) on the clipboard, permitting scripts to learn them arbitrarily will trigger safety dangers, so this API has extra safety restrictions. Initially, the Chrome browser stipulates that solely HTTPS protocol pages can use this API. Nonetheless, the event surroundings (localhost) permits using 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 robotically granted to the script, and the “learn permission” should be explicitly granted by the consumer. In different phrases, the script could be robotically 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 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 should you paste the related code into the developer software and run it straight, an error could also be reported as a result of the present web page right now is the window of the developer software, not an internet web page.

In case you paste the above code into the developer software and run it, an error can 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 rapidly click on on the web page window of the browser earlier than calling the perform to show it into the present web page.

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

Clipboard object

clipboard.readText()

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

Within the above instance, after the consumer clicks on the web page, the textual content within the clipboard can be output. Be aware that the browser will pop up a dialog field right now, 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. Right now, you should utilize the strive...catch construction to deal with errors.

clipboard.learn()

The clipboard.learn() methodology is used to repeat the info within the clipboard, which could be textual content information or binary information (reminiscent of footage). This methodology requires specific permission from the consumer. This methodology returns a Promise object. As soon as the state of the article turns into resolved, an array could 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 out there for the clip merchandise. For instance, a clip merchandise could 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 info 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 info of that sort. This parameter is required, in any other case, an error can be reported.

clipboard.writeText()

The clipboard.writeText() methodology is used to write down textual content content material to the clipboard.

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

clipboard.write()

The clipboard.write() methodology is used to write down arbitrary information to the clipboard, which could be textual content information or binary information. This methodology accepts a ClipboardItem occasion as a parameter, which represents the info written to the clipboard.

Within the above instance, the script writes an image to the clipboard. Be aware 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 identify of the article is the MIME sort of the info, and the important thing worth is the info itself. The next instance is to write down the worth of the identical clip merchandise in a number of codecs to the clipboard, one is textual content information, and the opposite is binary information for pasting on totally different events.

When the consumer places information into the clipboard, the copy occasion can 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 comprises the clipboard information. It’s an object with the next properties and strategies.

  • Occasion.clipboardData.setData(sort, information) : To change the clipboard information, it’s good to specify the info sort.
  • Occasion.clipboardData.getData(sort) : To acquire clipboard information, it’s good to specify the info sort.
  • Occasion.clipboardData.clearData([type]) : Clear clipboard information, you possibly can specify the info sort. If you don’t specify the sort, all kinds of information can be cleared.
  • Occasion.clipboardData.objects : An array-like object comprises all clip objects, however often 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 lower occasion is triggered when the consumer performs a chopping operation. Its processing is strictly the identical because the copy occasion, and the lower information can be obtained from the Occasion.clipboardData property.

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

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