window.getSelection().toString() not working in Firefox (works in Chrome)

Question

When I highlight numbers on an <input type="number"> in Chrome, window.getSelection().toString() successfully gives me the highlighted text.

But this is not so in Firefox; it is always blank. Does anyone know why? This is really confusing since MDN getSelection documentation states it should work in Firefox 57.

Answer 1

This is a firefox bug. See https://bugzilla.mozilla.org/show_bug.cgi?id=85686

Very old one, not fixed yet.

I use the following code as workaround:

        function getSelectionText() {
            if (window.getSelection) {
                try {
                    var activeElement = document.activeElement;
                    if (activeElement && activeElement.value) {
                        // firefox bug https://bugzilla.mozilla.org/show_bug.cgi?id=85686
                        return activeElement.value.substring(activeElement.selectionStart, activeElement.selectionEnd);
                    } else {
                        return window.getSelection().toString();
                    }

                } catch (e) {
                }
            } else if (document.selection && document.selection.type != "Control") {
                // For IE
                return document.selection.createRange().text;
            }
        }