javascript tutorial - [Solved-4 Solutions] Trello access the user's clipboard - javascript - java script - javascript array

How does Trello access the user's clipboard?

We don't actually "access the user's clipboard", instead we help the user out a bit by selecting something useful when they press Ctrl+C. Sounds like you've figured it out; we take advantage of the fact that when you want to hit Ctrl+C, you have to hit the Ctrl key first. When the Ctrl key is pressed, we pop in a textarea that contains the text we want to end up on the clipboard, and select all the text in it, so the selection is all set when the Ccode> key is hit. (Then we hide the textarea when the Ctrl key comes up) Specifically, Trello does this:

TrelloClipboard = new class
  constructor: ->
    @value = ""

    $(document).keydown (e) =>
      # Only do this if there's something to be put on the clipboard, and it
      # looks like they're starting a copy shortcut
      if !@value || !(e.ctrlKey || e.metaKey)
        return

      if $(e.target).is("input:visible,textarea:visible")
        return

      # Abort if it looks like they've selected some text (maybe they're trying
      # to copy out a bit of the description or something)
      if window.getSelection?()?.toString()
        return

      if document.selection?.createRange().text
        return

      _.defer =>
        $clipboardContainer = $("#clipboard-container")
        $clipboardContainer.empty().show()
        $("<textarea id='clipboard'></textarea>")
        .val(@value)
        .appendTo($clipboardContainer)
        .focus()
        .select()

    $(document).keyup (e) ->
      if $(e.target).is("#clipboard")
        $("#clipboard-container").empty().hide()

  set: (@value) ->

In the DOM we've got

<div id="clipboard-container"><textarea id="clipboard"></textarea></div>

CSS for the clipboard stuff:

#clipboard-container {
  position: fixed;
  left: 0px;
  top: 0px;
  width: 0px;
  height: 0px;
  z-index: 100;
  display: none;
  opacity: 0;
}
#clipboard {
  width: 1px;
  height: 1px;       
  padding: 0px;
}

The CSS makes it so you can't actually see the textarea when it pops in ... but it's "visible" enough to copy from.

When you hover over a card, it calls

TrelloClipboard.set(cardUrl)

... so then the clipboard helper knows what to select when the Ctrl key is pressed.

three bugs with Trello's approach, which I know because I've faced them myself :)

The copy doesn't work in these scenarios:

function TrelloClipboard() {
    var me = this;

    var utils = {
        nodeName: function (node, name) {
            return !!(node.nodeName.toLowerCase() === name)
        }
    }
    var textareaId = 'simulate-trello-clipboard',
        containerId = textareaId + '-container',
        container, textarea

    var createTextarea = function () {
        container = document.querySelector('#' + containerId)
        if (!container) {
            container = document.createElement('div')
            container.id = containerId
            container.setAttribute('style', [, 'position: fixed;', 'left: 0px;', 'top: 0px;', 'width: 0px;', 'height: 0px;', 'z-index: 100;', 'opacity: 0;'].join(''))
            document.body.appendChild(container)
        }
        container.style.display = 'block'
        textarea = document.createElement('textarea')
        textarea.setAttribute('style', [, 'width: 1px;', 'height: 1px;', 'padding: 0px;'].join(''))
        textarea.id = textareaId
        container.innerHTML = ''
        container.appendChild(textarea)

        textarea.appendChild(document.createTextNode(me.value))
        textarea.focus()
        textarea.select()
    }

    var keyDownMonitor = function (e) {
        var code = e.keyCode || e.which;
        if (!(e.ctrlKey || e.metaKey)) {
            return
        }
        var target = e.target
        if (utils.nodeName(target, 'textarea') || utils.nodeName(target, 'input')) {
            return
        }
        if (window.getSelection && window.getSelection() && window.getSelection().toString()) {
            return
        }
        if (document.selection && document.selection.createRange().text) {
            return
        }
        setTimeout(createTextarea, 0)
    }

    var keyUpMonitor = function (e) {
        var code = e.keyCode || e.which;
        if (e.target.id !== textareaId || code !== 67) {
            return
        }
        container.style.display = 'none'
    }

    document.addEventListener('keydown', keyDownMonitor)
    document.addEventListener('keyup', keyUpMonitor)
}

TrelloClipboard.prototype.setValue = function (value) {
    this.value = value;
}

var clip = new TrelloClipboard();
clip.setValue("test");

var TrelloClipboard;

TrelloClipboard = new ((function () {
    function _Class() {
        this.value = "";
        $(document).keydown((function (_this) {
            return function (e) {
                var _ref, _ref1;
                if (!_this.value || !(e.ctrlKey || e.metaKey)) {
                    return;
                }
                if ($(e.target).is("input:visible,textarea:visible")) {
                    return;
                }
                if (typeof window.getSelection === "function" ? (_ref = window.getSelection()) != null ? _ref.toString() : void 0 : void 0) {
                    return;
                }
                if ((_ref1 = document.selection) != null ? _ref1.createRange().text : void 0) {
                    return;
                }
                return $.Deferred(function () {
                    var $clipboardContainer;
                    $clipboardContainer = $("#clipboard-container");
                    $clipboardContainer.empty().show();
                    return $("<textarea id='clipboard'></textarea>").val(_this.value).appendTo($clipboardContainer).focus().select();
                });
            };
        })(this));

        $(document).keyup(function (e) {
            if ($(e.target).is("#clipboard")) {
                return $("#clipboard-container").empty().hide();
            }
        });
    }

    _Class.prototype.set = function (value) {
        this.value = value;
    };

    return _Class;

})());