Get highlighted text

text.js

function getSelectionText() {
    var text = "";
    if (window.getSelection) {
        text = window.getSelection().toString();
    } else if (document.selection && document.selection.type != "Control") {
        text = document.selection.createRange().text;
    }
    return text;
}
var keysDown = {};

window.addEventListener("keyup", function(e){
	keysDown[e.keyCode] = false;
});
window.addEventListener("keydown", function(e){
	keysDown[e.keyCode] = true;
	// ctrl + `
	if(keysDown[192] && keysDown[17]){
		var text = getSelectionText();
		// do something with selected text
	}
});