JSFiddle - React, Tailwind, and code Playground

by sauravmishra

HTML

<div id="editable" contenteditable="true">Some editable text</div>

JavaScript

function getSelectionTextInfo(el) {
    var atStart = false, atEnd = false;
    var selRange, testRange;
    if (window.getSelection) {
        var sel = window.getSelection();
        if (sel.rangeCount) {
            selRange = sel.getRangeAt(0);
            testRange = selRange.cloneRange();

            testRange.selectNodeContents(el);
            testRange.setEnd(selRange.startContainer, selRange.startOffset);
            atStart = (testRange.toString() == "");

            testRange.selectNodeContents(el);
            testRange.setStart(selRange.endContainer, selRange.endOffset);
            atEnd = (testRange.toString() == "");
        }
    } else if (document.selection && document.selection.type != "Control") {
        selRange = document.selection.createRange();
        testRange = selRange.duplicate();
        
        testRange.moveToElementText(el);
        testRange.setEndPoint("EndToStart", selRange);
        atStart = (testRange.text == "");

        testRange.moveToElementText(el);
        testRange.setEndPoint("StartToEnd", selRange);
        atEnd = (testRange.text == "");
    }

    return { atStart: atStart, atEnd: atEnd };
}


document.getElementById("editable").onkeydown = function() {
    var selInfo = getSelectionTextInfo(this);
    console.log("At start: " + selInfo.atStart + ", at end: " + selInfo.atEnd);
}