Modifying the CSS of highlighted text with the help of JavaScript

Question

Modifying the CSS of highlighted text with the help of JavaScript

I am currently working on a JavaScript bookmarklet that will function as a highlighter, changing the background color of selected text on a webpage to yellow when the bookmarklet is clicked.

The code I have for retrieving the selected text is functioning correctly and returning the desired string:

function getSelectedText() {
    var selection = '';
    if (window.getSelection) {
        selection = window.getSelection();
    } else if (document.getSelection) {
        selection = document.getSelection();
    } else if (document.selection) {
        selection = document.selection.createRange().text;
    }
    return selection;
}

However, I am facing issues with a similar function that aims to change the CSS properties of the selected text using jQuery:

function applyHighlightToSelectedText() {
    var selectedText;
    if (window.getSelection) {
        selectedText = window.getSelection();
    } else if (document.getSelection) {
        selectedText = document.getSelection();
    } else if (document.selection) {
        selectedText = document.selection.createRange().text;
    }
    $(selectedText).css({'background-color' : 'yellow', 'font-weight' : 'bolder'});
}

Any suggestions on how to resolve this issue?

javascript jquery css highlight bookmarklet

Answer 1

Answer №1

If you're looking to change the background color easily, one method is to utilize the execCommand() function, which includes a command specifically for altering background colors in most up-to-date web browsers.

The code snippet below should effectively handle your request, even with selections that span across multiple elements. For non-Internet Explorer browsers, it activates designMode, sets a background color, and then deactivates designMode.

UPDATE:

This issue has been resolved in Internet Explorer 9.

function makeEditableAndHighlight(color) {
    var range, sel = window.getSelection();
    if (sel.rangeCount && sel.getRangeAt) {
        range = sel.getRangeAt(0);
    }
    document.designMode = "on";
    if (range) {
        sel.removeAllRanges();
        sel.addRange(range);
    }
    // Utilize HiliteColor as some browsers might apply BackColor to the entire block
    if (!document.execCommand("HiliteColor", false, color)) {
        document.execCommand("BackColor", false, color);
    }
    document.designMode = "off";
}

function highlight(color) {
    var range, sel;
    if (window.getSelection) {
       // For IE9 and other browsers
        try {
            if (!document.execCommand("BackColor", false, color)) {
                makeEditableAndHighlight(color);
            }
        } catch (ex) {
            makeEditableAndHighlight(color);
        }
    } else if (document.selection && document.selection.createRange) {
        // For older versions of Internet Explorer (8 and below)
        range = document.selection.createRange();
        range.execCommand("BackColor", false, color);
    }
}

Answer 2

If you're looking to change the background color easily, one method is to utilize the execCommand() function, which includes a command specifically for altering background colors in most up-to-date web browsers.

The code snippet below should effectively handle your request, even with selections that span across multiple elements. For non-Internet Explorer browsers, it activates designMode, sets a background color, and then deactivates designMode.

UPDATE:

This issue has been resolved in Internet Explorer 9.

function makeEditableAndHighlight(color) {
    var range, sel = window.getSelection();
    if (sel.rangeCount && sel.getRangeAt) {
        range = sel.getRangeAt(0);
    }
    document.designMode = "on";
    if (range) {
        sel.removeAllRanges();
        sel.addRange(range);
    }
    // Utilize HiliteColor as some browsers might apply BackColor to the entire block
    if (!document.execCommand("HiliteColor", false, color)) {
        document.execCommand("BackColor", false, color);
    }
    document.designMode = "off";
}

function highlight(color) {
    var range, sel;
    if (window.getSelection) {
       // For IE9 and other browsers
        try {
            if (!document.execCommand("BackColor", false, color)) {
                makeEditableAndHighlight(color);
            }
        } catch (ex) {
            makeEditableAndHighlight(color);
        }
    } else if (document.selection && document.selection.createRange) {
        // For older versions of Internet Explorer (8 and below)
        range = document.selection.createRange();
        range.execCommand("BackColor", false, color);
    }
}

Answer 3

Answer №2

Here's a basic demonstration of how it might operate. As mentioned by Zack, it's important to consider scenarios where the selection crosses multiple elements. This code snippet is not meant for direct implementation, but rather as a starting point for generating ideas. Tested in the Chrome browser.

let selectedText = window.getSelection();
let textContent = selectedText.toString();
let parentElement = $(selectedText.focusNode.parentElement);
let oldContent = parentElement.html();
let newContent = oldContent.replace(textContent, "<span class='highlight'>" + textContent + "</span>");
parentElement.html(newContent);

Answer 4

Here's a basic demonstration of how it might operate. As mentioned by Zack, it's important to consider scenarios where the selection crosses multiple elements. This code snippet is not meant for direct implementation, but rather as a starting point for generating ideas. Tested in the Chrome browser.

let selectedText = window.getSelection();
let textContent = selectedText.toString();
let parentElement = $(selectedText.focusNode.parentElement);
let oldContent = parentElement.html();
let newContent = oldContent.replace(textContent, "<span class='highlight'>" + textContent + "</span>");
parentElement.html(newContent);

Answer 5

Answer №3

In order to ensure that the highlighted section remains permanent, it is necessary to enclose the selection within a fresh DOM element (such as span) and then apply style attributes to it. I am not certain if jQuery has the capability to accomplish this task for you. It is important to remember that selections may cross over element boundaries, resulting in the need to introduce numerous new elements in the general scenario.

Answer 6

In order to ensure that the highlighted section remains permanent, it is necessary to enclose the selection within a fresh DOM element (such as span) and then apply style attributes to it. I am not certain if jQuery has the capability to accomplish this task for you. It is important to remember that selections may cross over element boundaries, resulting in the need to introduce numerous new elements in the general scenario.

Answer 7

Answer №4

Check out an example I created at http://www.jsfiddle.net/hbwEE/3/

This example does not consider selections that span multiple elements. (Internet Explorer will work but might mess up the HTML structure a bit.)

Answer 8

Check out an example I created at http://www.jsfiddle.net/hbwEE/3/

This example does not consider selections that span multiple elements. (Internet Explorer will work but might mess up the HTML structure a bit.)

Answer 9

Answer №5

For Mozilla Firefox, the ::-moz-selection pseudo-class can be utilized.
When working with Webkit browsers, opt for the ::selection pseudo-class.

Answer 10

For Mozilla Firefox, the ::-moz-selection pseudo-class can be utilized.
When working with Webkit browsers, opt for the ::selection pseudo-class.

Answer 11

Answer №6

I appreciate Tim's solution for its efficiency and cleanliness, although it does limit the possibility of interacting with highlights.

Directly adding inline elements around text can be disruptive to the flow and cause complications in more intricate scenarios,

Instead, I propose a unique workaround that

determines the precise layout of each line of selected text (regardless of their position),
then places colored, semi-transparent inline-block elements at the end of the document body.

An illustration of this approach can be seen in this chrome extension.

This tool utilizes the API provided by this library to obtain the exact layout of each selected line.

Answer 12

I appreciate Tim's solution for its efficiency and cleanliness, although it does limit the possibility of interacting with highlights.

Directly adding inline elements around text can be disruptive to the flow and cause complications in more intricate scenarios,

Instead, I propose a unique workaround that

determines the precise layout of each line of selected text (regardless of their position),
then places colored, semi-transparent inline-block elements at the end of the document body.

An illustration of this approach can be seen in this chrome extension.

This tool utilizes the API provided by this library to obtain the exact layout of each selected line.

Answer 13

Answer №7

If you're looking to add custom highlights to your webpage, the CSS Custom Highlight API is the way to go. This API allows you to mark specific ranges in JavaScript with a named highlight style, and then define the appearance of that highlight using CSS. The result is a persistent highlight effect that resembles text selection.

For example:

<style>
  div::highlight(foo) {
    background-color: green;
  }
</style>
<div id="highlighted">This is highlighted text</div>
<script>
  let r = new Range();
  r.setStart(highlighted, 0);
  r.setEnd(highlighted, 1);
  let h = new Highlight(r);
  CSS.highlights.set('foo', h);
</script>

Answer 14

If you're looking to add custom highlights to your webpage, the CSS Custom Highlight API is the way to go. This API allows you to mark specific ranges in JavaScript with a named highlight style, and then define the appearance of that highlight using CSS. The result is a persistent highlight effect that resembles text selection.

For example:

<style>
  div::highlight(foo) {
    background-color: green;
  }
</style>
<div id="highlighted">This is highlighted text</div>
<script>
  let r = new Range();
  r.setStart(highlighted, 0);
  r.setEnd(highlighted, 1);
  let h = new Highlight(r);
  CSS.highlights.set('foo', h);
</script>

Modifying the CSS of highlighted text with the help of JavaScript

Answer №1

Answer №2

Answer №3

Answer №4

Answer №5

Answer №6

Answer №7

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