AngularJS – Copy to Clipboard Directive

Yesterday I was requested to create a “copy to clipboard” behavior in an AngularJS application I’m building. The main idea was to mark some content which has a meaning and to enable the user to copy the “meaning” to the clipboard by pressing a button.

Here is the directive I ended up with:

(function () {
    'use strict';
    angular.
        module("demo").
        directive("copyToClipboard", copyClipboardDirective);

    function copyClipboardDirective() {
        var clip;

        function link(scope, element) {
            function clipboardSimulator() {
                var self = this,
                    textarea,
                    container;

                function createTextarea() {
                    if (!self.textarea) {
                        container = document.createElement('div');
                        container.id = 'simulate-clipboard-container';
                        container.setAttribute('style', ['position: fixed;', 'left: 0px;', 'top: 0px;', 'width: 0px;', 'height: 0px;', 'z-index: 100;', 'opacity: 0;', 'display: block;'].join(''));
                        document.body.appendChild(container);

                        textarea = document.createElement('textarea');
                        textarea.setAttribute('style', ['width: 1px;', 'height: 1px;', 'padding: 0px;'].join(''));
                        textarea.id = 'simulate-clipboard';
                        self.textarea = textarea;
                        container.appendChild(textarea);
                    }
                }

                createTextarea();
            }

            clipboardSimulator.prototype.copy = function() {
                this.textarea.innerHTML = '';
                this.textarea.appendChild(document.createTextNode(scope.textToCopy));
                this.textarea.focus();
                this.textarea.select();
                setTimeout(function() {
                    document.execCommand('copy');
                }, 20);
            };

            clip = new clipboardSimulator();

            element[0].addEventListener('click', function() {
                clip.copy();
            });
        }

        return {
            restrict: 'A',
            link: link,
            scope: {
                textToCopy: '='
            }
        };
    }
}());

The main idea is borrowed from a StackOverflow answer – How does Trello access the user’s clipboard?

I use an invisible element container to wrap a textarea which will hold the copied content. The directive model, textToCopy, is used to get the text that I copy, which means that all the directive user needs to do is to hold in that model the text he/she wants to copy. Once the button is clicked, I put the textToCopy data in the textarea, call the textarea select function and use the document.execCommand(‘copy’) call to force the browser to copy the selected content to the clipboard.

Here is how you can use the directive on top of an element:

<button copy-to-clipboard text-to-copy="vm.someText">Copy to Clipboard</button>

someText will be a property of the vm object which will hold the text you want to copy (in my application vm is a controller that is used with the controllerAs property).

I hope that you will find this directive useful.