不能在输入类型文件中使用document.execCommand('copy') [英] can't use document.execCommand('copy') with input type file

问题描述

无法将textarea的内容复制到剪贴板 使用下面的代码.

can't copy the content of textarea to clipboard using the code below.

    <script>
    function copyText()
    {
    document.getElementById('in').click();
    call();
    }
    function call()
    {
    if(getComputedStyle(document.getElementById('butt')).opacity>0.5)
    {setTimeout(call,100);return;}

    var ta=window.document.createElement("textarea");
    window.document.body.appendChild(ta);
    ta.value="this text should be in clipboard";
    ta.focus();
    ta.selectionStart=0;
    ta.selectionEnd=ta.value.length;
    ta.addEventListener('keypress', function(){window.document.execCommand('copy');});
    var event = new Event('keypress');
    ta.dispatchEvent(event) ;
    }
    </script>
    <button id='butt' onClick='copyText()'>copy text</button>
    <input id='in' type='file' style='display:none;'/>
    <style>
    #butt
    {opacity:0.5;}
    #butt:hover
    {opacity:1;}
    </style>

而如果我在return语句之前的if块中的setTimeout(call,100)之后添加alert().
正在复制文本.
每个浏览器在chrome，opera和firefox上进行尝试的方式都相同.
我正在使用上述结构复制用户打开的文件的base64编码文本.

while if i add an alert() after the setTimeout(call,100) in the if block before return statement.
Text is being copied.
tried it on chrome,opera and firefox every browser responded the same way.
I am using the above structure to copy the base64 encoded text of the file that user opened.

推荐答案

大多数浏览器只会以这种方式将文本从真实用户事件(如单击或按键)中直接启动的Javascript复制到剪贴板，而不会来自setTimeout().因此，如果您的代码采用setTimeout()路径，则可能无法将文本复制到剪贴板.您不能只制造按键事件-此限制的全部要点是需要一个真实的用户事件，而不是由代码制造的事件.

Most browsers will only copy text to the clipboard in this way from Javascript that was directly initiated from a real user event (like a click or a key) and not from a setTimeout(). So, if your code takes the setTimeout() path, then it is likely that the copying of the text to the clipboard will not work. You can't just manufacture the keypress event - the whole point of this restriction is to require a real user event, not one manufactured by code.

如果您有兴趣，可以使用以下经过测试的功能将文本复制到

In case you're interested, here's a tested function to copy text to the clipboard in this answer. It has the same restrictions as any other code - it must be initiated from Javascript that is called by a real user event and it works in modern versions of Chrome, Firefox and IE, but not in Safari.

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