navigator.clipboard is undefined

Why is navigator.clipboard always undefined in the following snippet?

var clipboard = navigator.clipboard;
if (clipboard == undefined) {
    console.log('clipboard is undefined');
} else {
    clipboard.writeText('stuff to write').then(function() {
        console.log('Copied to clipboard successfully!');
    }, function() {
        console.error('Unable to write to clipboard. :-(');
    });
}

More on the clipboard API can be found here.

Chrome Version: 68.0.3440.106.

I'm sure this was working at some point, but no longer is. It's confusing because this table suggests that the Clipboard API is implemented in Chrome (has been for some time), but this table of specific API methods suggests that none of the methods of the API is supported??

Solution 1:

This requires a secure origin — either HTTPS or localhost (or disabled by running Chrome with a flag). Just like for ServiceWorker, this state is indicated by the presence or absence of the property on the navigator object.

https://developers.google.com/web/updates/2018/03/clipboardapi

This is noted in the spec with [SecureContext] on the interface: https://w3c.github.io/clipboard-apis/#dom-navigator-clipboard

You can check the state of window.isSecureContext to learn if that's the reason a feature is unavailable. Secure contexts | MDN

And yes, you should set up HSTS to make sure HTTP redirects to HTTPS.

Solution 2:

you can write an all-in-one wrapper function.

• if in secure context (https) : use navigator clipboard api
• if not : use the 'out of viewport hidden text area' trick

// return a promise
function copyToClipboard(textToCopy) {
    // navigator clipboard api needs a secure context (https)
    if (navigator.clipboard && window.isSecureContext) {
        // navigator clipboard api method'
        return navigator.clipboard.writeText(textToCopy);
    } else {
        // text area method
        let textArea = document.createElement("textarea");
        textArea.value = textToCopy;
        // make the textarea out of viewport
        textArea.style.position = "fixed";
        textArea.style.left = "-999999px";
        textArea.style.top = "-999999px";
        document.body.appendChild(textArea);
        textArea.focus();
        textArea.select();
        return new Promise((res, rej) => {
            // here the magic happens
            document.execCommand('copy') ? res() : rej();
            textArea.remove();
        });
    }
}

use :

copyToClipboard("I'm going to the clipboard !")
    .then(() => console.log('text copied !'))
    .catch(() => console.log('error'));

ps : do not try it in a repl like jsfiddle/copeden/...