Javascript Selection API
Get the text of the selection
let sel = document.getSelection();
let text = sel.toString();
console.log(text);Output
what the user selected
Alternatively, since the toString member function is called automatically by some functions when converting the object to a string, you don't always have to call it yourself.
console.log(document.getSelection());Deselect everything that is selected
let sel = document.getSelection();
sel.removeAllRanges();Select the contents of an element
let sel = document.getSelection();
let myNode = document.getElementById('element-to-select');
let range = document.createRange();
range.selectNodeContents(myNode);
sel.addRange(range);It may be necessary to first remove all the ranges of the previous selection, as most browsers don't support multiple ranges.