How to get selected text + n characters on sides?

Question

JavaScript

I found this function to get the selected text:

function getSelectionText() {
    var text = "";

    if (window.getSelection) {
        text = window.getSelection(5).toString();
    } else if (document.selection && document.selection.type != "Control") {
        text = document.selection.createRange().text;
    }

    return text;
}

but I can't figure out how to get what is selected by the user + 10 (for example) characters on the sides. Tell me, please, where to dig.

Answer 1

Here is a simple example, no checks. For document.selection is done in a similar way.

function getSelectionText(d) {
    var string = window.getSelection();
    return string.baseNode.data.substring(string.anchorOffset - d, string.focusOffset + d);
}
var string = getSelectionText(10);