javascript - How to make a link change the content of a paragraph on click? return false not working

I am learning to code JavaScript. In this script, I want a link to not go to its specified location, but to change the text in the paragraph before it. I have created a function to achieve it onclick, but the function is not able to return false.

<html>
<head>
    <title>Javascript Test #6</title>
    <script type="text/javascript">
        document.getElementById("links").onclick=writeData();
        function writeData()
            {
                document.getElementById("para").innerHTML="Changed Paragraph Content";
                return false;
            }
    </script>
</head>
<body>
    <p id="para">Unchanged Paragraph Content</p>
    <br/>
    <a id="links" href="javascript-return.html"> Click here to change the paragraph content </a>
</body>
</html>

<html>
<head>
    <title>Javascript Test #6</title>
    <script type="text/javascript">
        document.getElementById("links").onclick=writeData();
        function writeData()
            {
                document.getElementById("para").innerHTML="Changed Paragraph Content";
                return false;
            }
    </script>
</head>
<body>
    <p id="para">Unchanged Paragraph Content</p>
    <br/>
    <a id="links" href="javascript-return.html"> Click here to change the paragraph content </a>
</body>
</html>

Share Improve this question edited Jan 17, 2023 at 8:13 Brian Tompsett - 汤莱恩 5,89372 gold badges61 silver badges133 bronze badges asked Nov 18, 2011 at 7:54 Supratim Nayak 11 silver badge2 bronze badges

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2 Answers 2

Sorted by: Reset to default 3

document.getElementById("links").onclick=writeData;

Don't use the brackets. They force your function to evaluate. but you want to assign the function.

EDIT:

Of Course, you need to Assign your Function after the Document has been loaded. The way it is right now, there will be no element with id links when the assignment is executed. Basically, just put your script block below the links element.

<html>
<head>
    <title>Javascript Test #6</title>
</head>
<body>
    <p id="para">Unchanged Paragraph Content</p>
    <br/>
    <a id="links" href="javascript-return.html"> Click here to change the paragraph content </a>

    <script type="text/javascript">
        document.getElementById("links").onclick=writeData;
        function writeData()
        {
            document.getElementById("para").innerHTML="Changed Paragraph Content";
            return false;
        }
    </script>
</body>
</html>

EDIT (Using window.onload):

<html>
<head>
    <title>Javascript Test #6</title>
    <script type="text/javascript">
        window.onload = function() {
            document.getElementById("links").onclick=writeData;
        }

        function writeData()
        {
            document.getElementById("para").innerHTML="Changed Paragraph Content";
            return false;
        }
    </script>
</head>
<body>
    <p id="para">Unchanged Paragraph Content</p>
    <br/>
    <a id="links" href="javascript-return.html"> Click here to change the paragraph content </a>
</body>
</html>

When dealing with document.getElementById, you should ensure that at the time of the call, the elements are in DOM. Just use an inline click handler:

<html>
    <head>
    <title>Javascript Test #6</title>
    <script type="text/javascript">
        function writeData()
        {
            document.getElementById("para").innerHTML="Changed Paragraph Content";
            return false;
        }
    </script>
    </head>
    <body>
        <p id="para">Unchanged Paragraph Content</p>
        <br/>
        <a id="links" href="javascript-return.html" onclick="return writeData();">    Click here       to change the paragraph content </a>
    </body>
 </html>

Or, change the order of things: first have the DOM ready, and after that , insert you js script:

<html>
    <head>
    <title>Javascript Test #6</title>
    </head>
    <body>
        <p id="para">Unchanged Paragraph Content</p>
        <br/>
        <a id="links" href="javascript-return.html" onclick="return writeData();">    Click here       to change the paragraph content </a>
        <script type="text/javascript">
            document.getElementById("links").onclick=writeData;
            function writeData()
            {
                document.getElementById("para").innerHTML="Changed Paragraph Content";
                return false;
            }
        </script>
    </body>
 </html>

see it in action here: http://jsfiddle/2CpcF/

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2 Answers 2

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