How to create Show More and Show Less functionality for hiding text using JavaScript ?

A Show More and Show Less functionality can be useful in websites that are heavy in text, like news and magazine websites that contain a lot of articles on a single page. This can help the web page designer to give the user the freedom to read more or less text as needed. 

Approach: The amount of content displayed can be changed by clicking on the buttons. Instead of showing a complete paragraph on a webpage, only some part of the text is shown initially and a button is added which shows more of the text. The amount of text that should be displayed after and before they click on a button can be decided by the developer.

Example: The above approach can be implemented by using a simple if-else condition that checks the current status of the text and shows or hides it on that basis. The below example illustrates this method:

HTML

<style>
    /* Initially, hide the extra text that
        can be revealed with the button */
    #moreText {

        /* Display nothing for the element */
        display: none;
    }
</style>

<h1 style="color: green;">
    GeeksforGeeks
</h1>

<h3>Show More and Show Less Example</h3>

<p>
    GeeksforGeeks was born out of necessity-
    a need to provide a convenient and
    one-stop educational portal to all the
    students of Computer Science.
    <span id="points">...</span>

    <!-- Define the text that would be
            hidden by default and only shown
            when clicked on the button -->
    <span id="moreText"> This necessity was
        as personal to me as it was universal.
        This need combined with my passion for
        teaching resulted in GeeksforGeeks as
        we know today. My message to you, in
        our inaugural edition of Geeks Digest,
        would be that if you are looking for
        a problem to work on, you don’t need
        to look very far for it. All you should
        do is to look around yourself.
    </span>
</p>


<!-- Trigger toggleText() when the
        button is clicked -->
<button onclick="toggleText()" id="textButton">
    Show More
</button>

<script>
    function toggleText() {

        // Get all the elements from the page
        var points =
            document.getElementById("points");

        var showMoreText =
            document.getElementById("moreText");

        var buttonText =
            document.getElementById("textButton");

        // If the display property of the dots
        // to be displayed is already set to
        // 'none' (that is hidden) then this
        // section of code triggers
        if (points.style.display === "none") {

            // Hide the text between the span
            // elements
            showMoreText.style.display = "none";

            // Show the dots after the text
            points.style.display = "inline";

            // Change the text on button to
            // 'Show More'
            buttonText.innerHTML = "Show More";
        }

        // If the hidden portion is revealed,
        // we will change it back to be hidden
        else {

            // Show the text between the
            // span elements
            showMoreText.style.display = "inline";

            // Hide the dots after the text
            points.style.display = "none";

            // Change the text on button
            // to 'Show Less'
            buttonText.innerHTML = "Show Less";
        }
    }
</script>

Output: