JavaScript prohibits pasting

JavaScript Disable Pasting

In most web applications, users can use the paste function to paste text, images, and other media content from the clipboard onto a web page. Although this function is convenient, it sometimes brings security risks and user experience problems. This article explains how to disable pasting using JavaScript.

1. Paste event

In JavaScript, we can use the onpaste event to handle the paste operation. This event is fired when the user pastes content into a text field or editable area.

The following is a simple example demonstrating how to use the onpaste event.

<input type="text" onpaste="alert('禁止粘贴！'); return false;">

When the user tries to paste in the text box, a prompt box will pop up, prompting the user that the paste operation cannot be performed.

2. Disable pasting

If we want to completely prohibit users from pasting in the text field or editable area, we can set the return value of the onpaste event to false. In this way, no matter what method the user enables for pasting operations, it will be prohibited.

<textarea onpaste="return false;"></textarea>

In this example, we prohibit the user from pasting in the text field. Regardless of whether the user uses the shortcut Ctrl V or right-clicks and selects paste, the paste operation will be blocked.

3. Clear the pasted content

Sometimes, we hope that users can paste, but the pasted content needs to be cleared. This requirement usually occurs in scenarios where certain types of content need to be filtered out, or where pasted content needs to be processed in some way.

In the following example, we show how to clear all HTML tags pasted from the clipboard into the text box:

<input type="text" onpaste="event.preventDefault(); var text = (event.originalEvent || event).clipboardData.getData('text/plain'); text = text.replace(/<[^>]*>/g, ''); document.execCommand('insertText', false, text);">

When the user pastes in the text box, the onpaste event The JavaScript code will be triggered and executed. This code prevents the default paste operation using event.preventDefault(). It then gets the plain text from the clipboard and processes it, removing all HTML tags. Finally, use document.execCommand() to insert the processed text into the text box.

4. Conclusion

In this article, we introduced the method of using JavaScript to disable the paste function and clear the pasted content. These technologies can help us improve the security of web applications and improve user experience. However, in actual use, we need to carefully evaluate the impact of these functions on the application to avoid unnecessary problems and difficulties.

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