如何使用 JavaScript 检测 Ctrl+V、Ctrl+C？

Question

How to detect Ctrl + V , Ctrl + C using JavaScript?

I need to restrict pasting in my textareas, end user should not copy and paste the content, user should only type text in textarea.

How can I achieve this?

Answer 1

I just did this out of interest. I agree it's not the right thing to do, but I think it should be the op's decision... Also the code could easily be extended to add functionality, rather than take it away (like a more advanced clipboard, or Ctrl + s triggering a server-side save).

 $(document).ready(function() { var ctrlDown = false, ctrlKey = 17, cmdKey = 91, vKey = 86, cKey = 67; $(document).keydown(function(e) { if (e.keyCode == ctrlKey || e.keyCode == cmdKey) ctrlDown = true; }).keyup(function(e) { if (e.keyCode == ctrlKey || e.keyCode == cmdKey) ctrlDown = false; }); $(".no-copy-paste").keydown(function(e) { if (ctrlDown && (e.keyCode == vKey || e.keyCode == cKey)) return false; }); // Document Ctrl + C/V $(document).keydown(function(e) { if (ctrlDown && (e.keyCode == cKey)) console.log("Document catch Ctrl+C"); if (ctrlDown && (e.keyCode == vKey)) console.log("Document catch Ctrl+V"); }); });

 <script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script> <h3>Ctrl+c Ctrl+v disabled</h3> <textarea class="no-copy-paste"></textarea> <br><br> <h3>Ctrl+c Ctrl+v allowed</h3> <textarea></textarea>

Also just to clarify, this script requires the jQuery library.

Codepen demo

EDIT: removed 3 redundant lines (involving e.which) thanks to Tim Down's suggestion (see comments)

EDIT: added support for Macs ( cmd key instead of ctrl )

Answer 2

With jquery you can easy detect copy, paste, etc by binding the function:

$("#textA").bind('copy', function() {
    $('span').text('copy behaviour detected!')
}); 
$("#textA").bind('paste', function() {
    $('span').text('paste behaviour detected!')
}); 
$("#textA").bind('cut', function() {
    $('span').text('cut behaviour detected!')
});

More information here: http://www.mkyong.com/jquery/how-to-detect-copy-paste-and-cut-behavior-with-jquery/

Answer 3

While it can be annoying when used as an anti-piracy measure, I can see there might be some instances where it'd be legitimate, so:

function disableCopyPaste(elm) {
    // Disable cut/copy/paste key events
    elm.onkeydown = interceptKeys

    // Disable right click events
    elm.oncontextmenu = function() {
        return false
    }
}

function interceptKeys(evt) {
    evt = evt||window.event // IE support
    var c = evt.keyCode
    var ctrlDown = evt.ctrlKey||evt.metaKey // Mac support

    // Check for Alt+Gr (http://en.wikipedia.org/wiki/AltGr_key)
    if (ctrlDown && evt.altKey) return true

    // Check for ctrl+c, v and x
    else if (ctrlDown && c==67) return false // c
    else if (ctrlDown && c==86) return false // v
    else if (ctrlDown && c==88) return false // x

    // Otherwise allow
    return true
}

I've used event.ctrlKey rather than checking for the key code as on most browsers on Mac OS X Ctrl / Alt "down" and "up" events are never triggered, so the only way to detect is to use event.ctrlKey in the eg c event after the Ctrl key is held down. I've also substituted ctrlKey with metaKey for macs.

Limitations of this method:

• Opera doesn't allow disabling right click events

• Drag and drop between browser windows can't be prevented as far as I know.

• The edit -> copy menu item in eg Firefox can still allow copy/pasting.

• There's also no guarantee that for people with different keyboard layouts/locales that copy/paste/cut are the same key codes (though layouts often just follow the same standard as English), but blanket "disable all control keys" mean that select all etc will also be disabled so I think that's a compromise which needs to be made.

Answer 4

There's another way of doing this: onpaste , oncopy and oncut events can be registered and cancelled in IE, Firefox, Chrome, Safari (with some minor problems), the only major browser that doesn't allow cancelling these events is Opera.

As you can see in my other answer intercepting Ctrl + v and Ctrl + c comes with many side effects, and it still doesn't prevent users from pasting using the Firefox Edit menu etc.

function disable_cutcopypaste(e) {
    var fn = function(evt) {
        // IE-specific lines
        evt = evt||window.event
        evt.returnValue = false

        // Other browser support
        if (evt.preventDefault) 
            evt.preventDefault()
        return false
    }
    e.onbeforepaste = e.onbeforecopy = e.onbeforecut = fn
    e.onpaste = e.oncopy = e.oncut = fn
}

Safari still has some minor problems with this method (it clears the clipboard in place of cut/copy when preventing default) but that bug appears to have been fixed in Chrome now.

See also: http://www.quirksmode.org/dom/events/cutcopypaste.html and the associated test page http://www.quirksmode.org/dom/events/tests/cutcopypaste.html for more information.

Answer 5

Live Demo : http://jsfiddle.net/abdennour/ba54W/

$(document).ready(function() {

    $("#textA").bind({
        copy : function(){
            $('span').text('copy behaviour detected!');
        },
        paste : function(){
            $('span').text('paste behaviour detected!');
        },
        cut : function(){
            $('span').text('cut behaviour detected!');
        }
    });

}); 

Answer 6

Short solution for preventing user from using context menu, copy and cut in jQuery:

jQuery(document).bind("cut copy contextmenu",function(e){
    e.preventDefault();
});

Also disabling text selection in CSS might come handy:

.noselect {  
    -webkit-touch-callout: none;
    -webkit-user-select: none;
    -khtml-user-select: none;
    -moz-user-select: none;
    -ms-user-select: none;
     user-select: none;
}

Answer 7

If you use the ctrlKey property, you don't need to maintain state.

   $(document).keydown(function(event) {
      // Ctrl+C or Cmd+C pressed?
      if ((event.ctrlKey || event.metaKey) && event.keyCode == 67) {
         // Do stuff.
      }

      // Ctrl+V or Cmd+V pressed?
      if ((event.ctrlKey || event.metaKey) && event.keyCode == 86) {
         // Do stuff.
      }

      // Ctrl+X or Cmd+X pressed?
      if ((event.ctrlKey || event.metaKey) && event.keyCode == 88) {
         // Do stuff.
      } 
    }

Answer 8

Another approach (no plugin needed) it to just use ctrlKey property of the event object that gets passed in. It indicates if Ctrl was pressed at the time of the event, like this:

$(document).keypress("c",function(e) {
  if(e.ctrlKey)
    alert("Ctrl+C was pressed!!");
});

See also jquery: keypress, ctrl+c (or some combo like that) .

Answer 9

而不是onkeypress，使用onkeydown。

<input type="text" onkeydown="if(event.ctrlKey && event.keyCode==86){return false;}" name="txt">

Answer 10

I wrote a jQuery plugin, which catches keystrokes. It can be used to enable multiple language script input in html forms without the OS (except the fonts). Its about 300 lines of code, maybe you like to take a look:

• http://miku.github.com/jquery-retype

Generally, be careful with such kind of alterations. I wrote the plugin for a client because other solutions weren't available.

Answer 11

You can use this code for rightclick, CTRL + C , CTRL + V , CTRL + X detect and prevent their action

$(document).bind('copy', function(e) {
        alert('Copy is not allowed !!!');
        e.preventDefault();
    }); 
    $(document).bind('paste', function() {
        alert('Paste is not allowed !!!');
        e.preventDefault();
    }); 
    $(document).bind('cut', function() {
        alert('Cut  is not allowed !!!');
        e.preventDefault();
    });
    $(document).bind('contextmenu', function(e) {
        alert('Right Click  is not allowed !!!');
        e.preventDefault();
    });

Answer 12

Another simple way using Jquery:

$(document).keydown( function(e)
{
    if (e.ctrlKey && e.key == 'c')
    {
        console.log('got ctrl c');
    }
    else if (e.ctrlKey && e.key == 'v')
    {
        console.log('got ctrl v');
    }
});

Answer 13

Don't forget that, while you might be able to detect and block Ctrl + C / V , you can still alter the value of a certain field.
Best example for this is Chrome's Inspect Element function, this allows you to change the value-property of a field.

Answer 14

i already have your problem and i solved it by the following code .. that accept only numbers

$('#<%= mobileTextBox.ClientID %>').keydown(function(e) {
            ///// e.which Values
            // 8  : BackSpace , 46 : Delete , 37 : Left , 39 : Rigth , 144: Num Lock 
            if (e.which != 8 && e.which != 46 && e.which != 37 && e.which != 39 && e.which != 144
                && (e.which < 96 || e.which > 105 )) {
                return false;
            }
        });

you can detect Ctrl id e.which == 17

Answer 15

A hook that allows for overriding copy events, could be used for doing the same with paste events. The input element cannot be display: none; or visibility: hidden; sadly

export const useOverrideCopy = () => {
  const [copyListenerEl, setCopyListenerEl] = React.useState(
    null as HTMLInputElement | null
  )
  const [, setCopyHandler] = React.useState<(e: ClipboardEvent) => void | null>(
    () => () => {}
  )
  // appends a input element to the DOM, that will be focused.
  // when using copy/paste etc, it will target focused elements
  React.useEffect(() => {
    const el = document.createElement("input")  
    // cannot focus a element that is not "visible" aka cannot use display: none or visibility: hidden
    el.style.width = "0"
    el.style.height = "0"
    el.style.opacity = "0"
    el.style.position = "fixed"
    el.style.top = "-20px"
    document.body.appendChild(el)
    setCopyListenerEl(el)
    return () => {
      document.body.removeChild(el)
    }
  }, [])
  // adds a event listener for copying, and removes the old one 
  const overrideCopy = (newOverrideAction: () => any) => {
    setCopyHandler((prevCopyHandler: (e: ClipboardEvent) => void) => {
      const copyHandler = (e: ClipboardEvent) => {
        e.preventDefault()
        newOverrideAction()
      }
      copyListenerEl?.removeEventListener("copy", prevCopyHandler)
      copyListenerEl?.addEventListener("copy", copyHandler)
      copyListenerEl?.focus() // when focused, all copy events will trigger listener above
      return copyHandler
    })
  }
  return { overrideCopy }
}

Used like this:

const customCopyEvent = () => {
    console.log("doing something")
} 
const { overrideCopy } = useOverrideCopy()
overrideCopy(customCopyEvent)

Every time you call overrideCopy it will refocus and call your custom event on copy.

Answer 16

If anyone is interested in a simple vanilla JavaScript approach, see below.

      let ctrlActive = false;
      let cActive = false;
      let vActive = false

      document.body.addEventListener('keyup', event => {
        if (event.key == 'Control') ctrlActive = false;
        if (event.code == 'KeyC') cActive = false;
        if (event.code == 'KeyV') vActive = false;
      })

      document.body.addEventListener('keydown', event => {
        if (event.key == 'Control') ctrlActive = true;
        if (ctrlActive == true && event.code == 'KeyC') {

          // this disables the browsers default copy functionality
          event.preventDefault()

          // perform desired action(s) here...
          console.log('The CTRL key and the C key are being pressed simultaneously.')

        }

        if (ctrlActive == true && event.code == 'KeyV') {

          // this disables the browsers default paste functionality
          event.preventDefault()

          // perform desired action(s) here...
          console.log('The CTRL key and the V key are being pressed simultaneously.')

        }

      })

The code above would disable the default copy in the browser. If you'd like keep the copy functionality in the browser, just comment out this bit: event.preventDefault() and you can then run any desired actions while allowing the user to copy content.

Answer 17

element.addEventListener('keydown', function (e) {
    if (e.key == 'c' && e.ctrlKey) {
        e.preventDefault(); // prevent from copying
    }
    if (e.key == 'v' && e.ctrlKey) {
        e.preventDefault(); // prevent from pasting
    }
}

Answer 18

您可以监听 keypress 事件，如果它与特定的键码匹配，则停止默认事件（输入文本）

Answer 19

Important note

I was using e.keyCode for a while and i detected that when i press ctrl + . , This attribute returns a wrong number, 190, while the ascii code of . is 46!

So you should use e.key.toUpperCase().charCodeAt(0) instead of e.keyCode .

Answer 20

function noCopyMouse(e) {
    if (event.button == 2 || event.button == 3) {
        alert('You are prompted to type this twice for a reason!');
        return false;
    }
    return true;
}

function noCopyKey(e) {
    var forbiddenKeys = new Array('c','x','v');
    var isCtrl;

        if(window.event) {
        if(window.event.ctrlKey)
            isCtrl = true;
        else
            isCtrl = false;
        }
        else {
                if(e.ctrlKey)
                    isCtrl = true;
                else
                    isCtrl = false;
        }

    if(isCtrl) {
        for(i=0; iif(forbiddenKeys[i] == String.fromCharCode(window.event.keyCode).toLowerCase()) {
                alert('You are prompted to type this twice for a reason!');
                return false;
            }
            }
    }
    return true;
}

And now to reference those methods in the textboxes that you wish to restrict:

<input name="txtTest" id="txtTest" type="textbox" onmousedown="javascript:return noCopyMouse(event);" onkeykown="javascript:return noCopyKey(event);"  />

Answer 21

There is some ways to prevent it.

However the user will be always able to turn the javascript off or just look on the source code of the page.

Some examples (require jQuery)

/**
* Stop every keystroke with ctrl key pressed
*/
$(".textbox").keydown(function(){
    if (event.ctrlKey==true) {
        return false;
    }
});

/**
* Clear all data of clipboard on focus
*/
$(".textbox").focus(function(){
    if ( window.clipboardData ) {
        window.clipboardData.setData('text','');
    }
});

/**
* Block the paste event
*/
$(".textbox").bind('paste',function(e){return false;});

Edit: How Tim Down said, this functions are all browser dependents.