Lower, Copy and Paste in JavaScript
The browser permits JavaScript scripts to learn and write to the clipboard, and robotically 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. Nevertheless, generally 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,lowerandpasteOccasions
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, lower, and paste.
Doc.execCommand('copy')— copyDoc.execCommand('lower')— lowerDoc.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 could 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 aspect.
Drawback
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. In the event you copy/paste a considerable amount of knowledge, the web page will freeze. Some browsers may also 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 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 could actually put arbitrary content material (akin 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 implies that the present browser doesn’t help this API (you may see the total compatibly desk on Can I take advantage of…). Since customers could put delicate knowledge (akin 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. Nevertheless, 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” have to be explicitly granted by the consumer. In different phrases, the script may 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.
As well as, it ought to be famous that what the script reads is at all times 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 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 online web page.
In the event you paste the above code into the developer software and run it, an error will likely 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 determined by 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 perform 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 will likely be reported.
Clipboard object
clipboard.readText()
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 will likely be output. Be aware that the browser will pop up a dialog field at the moment, 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 need to use the attempt...catch construction to deal with errors.
clipboard.learn()
The clipboard.learn() methodology is used to repeat the info within the clipboard, which may be textual content knowledge or binary knowledge (akin 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.sorts property and a clipboardItem.getType() methodology. The clipboardItem.sorts property returns an array whose members are the MIME sorts 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 sorts (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 will likely be reported.
clipboard.writeText()
The clipboard.writeText() methodology is used to jot down 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 attempt...catch to stop errors.
clipboard.write()
The clipboard.write() methodology is used to jot down 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 info written to the clipboard.
Within the above instance, the script writes an image to the clipboard. Be aware that the Chrome browser presently (till this author writes this text) solely helps writing photos 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 title of the item is the MIME sort of the info, and the important thing worth is the info itself. The next instance is to jot down 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 will likely 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, you must specify the info sort.Occasion.clipboardData.getData(sort): To acquire clipboard knowledge, you must specify the info sort.Occasion.clipboardData.clearData([type]): Clear clipboard knowledge, you may specify the info sort. If you don’t specify the sort, all kinds of knowledge will likely be cleared.Occasion.clipboardData.objects: An array-like object accommodates 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 slicing operation. Its processing is precisely the identical because the copy occasion, and the lower knowledge can be obtained from the Occasion.clipboardData property.
When the consumer makes use of the clipboard knowledge to stick, the paste occasion will likely be triggered. The next instance is to intercept the paste operation, the info within the clipboard is taken out by the script.
