How to Highlight Selected Text with a Background Color Using JavaScript?

Changing the CSS of Selected Text Using JavaScript

To highlight selected text on a webpage, you can use the execCommand() function, which allows you to change the background color in modern browsers.

To achieve this, you can use the following function:

function highlight(colour) {
    var range, sel;
    if (window.getSelection) {
        // IE9 and non-IE
        try {
            if (!document.execCommand("BackColor", false, colour)) {
                makeEditableAndHighlight(colour);
            }
        } catch (ex) {
            makeEditableAndHighlight(colour)
        }
    } else if (document.selection && document.selection.createRange) {
        // IE <= 8 case
        range = document.selection.createRange();
        range.execCommand("BackColor", false, colour);
    }
}

function makeEditableAndHighlight(colour) {
    var range, sel = window.getSelection();
    if (sel.rangeCount &amp;&amp; sel.getRangeAt) {
        range = sel.getRangeAt(0);
    }
    document.designMode = "on";
    if (range) {
        sel.removeAllRanges();
        sel.addRange(range);
    }
    // Use HiliteColor since some browsers apply BackColor to the whole block
    if (!document.execCommand("HiliteColor", false, colour)) {
        document.execCommand("BackColor", false, colour);
    }
    document.designMode = "off";
}

This function checks for the selection range and applies the specified background color using execCommand(). It handles both IE and non-IE browsers, ensuring cross-browser compatibility.

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