javascript - Style.display blocknone problems - Stack Overflow

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I was planning on making a personal project with JavaScript until I encountered a problem. I have a table that's "Invisible" with css "style.display=none" but when I try to make it "visible" I get "Uncaught TypeError: Cannot read property 'style' of null".

JavaScript Code below:

    function attack(){
        document.getElementById("list").style.display="block";
        document.getElementById("message").innerHTML="";
    }
    function fire(){    
        var y=document.getElementById("message");   
        var x=document.getElementById("demo");
        var z=document.getElementById("att");
        x.innerHTML=3;
   }
function disappear(){
    document.getElementById("list").style.display="none";   
    document.getElementById("message").innerHTML="<center>Wild SlayerZach has appeared.</center>";
}

HTML below:

<body onload="disappear()">
    <table border="1" >
        <tr>
            <td><img id="SHP" src="Hp/HPSlayerzach/hp2.png"/></td>
            <td></td>
            <td><img src="characters/slayerzach/slayerzach.png"/></td>
        </tr>
        <tr>
            <td><p id="demo"></p></td>
            <td ><img id="att" src="backgrounds/spacer1.png"/></td>
            <td></td>
        </tr>
        <tr>
            <td><img align="right" src="characters/fighterdan13/fighterDan13.gif"/></td>
            <td></td>
            <td><img id="FHP" src="hp/HPFighterdan13/hp1.png"/></td>
        </tr>
        <tr>
            <td id="message" colspan="2" background="backgrounds/backgroundText.png">
                <center><table border="0" id="list">
                    <tr>
                        <td style="font-family:verdana;font-size:15px"><center><a onclick="fire()">FIRE</a></center></td>
                        <td style="font-family:verdana;font-size:15px"><center>LIGHTNING</center></td>
                    </tr>
                    <tr>
                        <td style="font-family:verdana;font-size:15px"><center>WATER</center></td>
                        <td style="font-family:verdana;font-size:15px"><center>EARTH</center></td>
                    </tr>
                </table></center>
            </td>
            <td>
                <center><table border="0" background="backgrounds/backgroundmenu.png">
                    <tr>
                        <td><button id="butAtt" onclick="attack()">Attack</button></td>
                        <td><button id="butItems" disabled>Items</button></td>
                    </tr>
                    <tr>
                        <td colspan="2"><center><button id="butRun" style="width:110px; height:25px;" disabled>Run</button><center></td>
                    </tr>
                </table></center>
            </td>
        </tr>
    </table>      
</body>

I was planning on making a personal project with JavaScript until I encountered a problem. I have a table that's "Invisible" with css "style.display=none" but when I try to make it "visible" I get "Uncaught TypeError: Cannot read property 'style' of null".

JavaScript Code below:

    function attack(){
        document.getElementById("list").style.display="block";
        document.getElementById("message").innerHTML="";
    }
    function fire(){    
        var y=document.getElementById("message");   
        var x=document.getElementById("demo");
        var z=document.getElementById("att");
        x.innerHTML=3;
   }
function disappear(){
    document.getElementById("list").style.display="none";   
    document.getElementById("message").innerHTML="<center>Wild SlayerZach has appeared.</center>";
}

HTML below:

<body onload="disappear()">
    <table border="1" >
        <tr>
            <td><img id="SHP" src="Hp/HPSlayerzach/hp2.png"/></td>
            <td></td>
            <td><img src="characters/slayerzach/slayerzach.png"/></td>
        </tr>
        <tr>
            <td><p id="demo"></p></td>
            <td ><img id="att" src="backgrounds/spacer1.png"/></td>
            <td></td>
        </tr>
        <tr>
            <td><img align="right" src="characters/fighterdan13/fighterDan13.gif"/></td>
            <td></td>
            <td><img id="FHP" src="hp/HPFighterdan13/hp1.png"/></td>
        </tr>
        <tr>
            <td id="message" colspan="2" background="backgrounds/backgroundText.png">
                <center><table border="0" id="list">
                    <tr>
                        <td style="font-family:verdana;font-size:15px"><center><a onclick="fire()">FIRE</a></center></td>
                        <td style="font-family:verdana;font-size:15px"><center>LIGHTNING</center></td>
                    </tr>
                    <tr>
                        <td style="font-family:verdana;font-size:15px"><center>WATER</center></td>
                        <td style="font-family:verdana;font-size:15px"><center>EARTH</center></td>
                    </tr>
                </table></center>
            </td>
            <td>
                <center><table border="0" background="backgrounds/backgroundmenu.png">
                    <tr>
                        <td><button id="butAtt" onclick="attack()">Attack</button></td>
                        <td><button id="butItems" disabled>Items</button></td>
                    </tr>
                    <tr>
                        <td colspan="2"><center><button id="butRun" style="width:110px; height:25px;" disabled>Run</button><center></td>
                    </tr>
                </table></center>
            </td>
        </tr>
    </table>      
</body>

Share Improve this question edited Feb 6, 2014 at 5:11 asked Feb 6, 2014 at 4:31 user3268382 51 gold badge1 silver badge5 bronze badges

The error indicates that document.getElementById("list") is not returning the element, but instead a null value. Can you make a fiddle/demo? If the element exists with that ID, it should be fine, so I'm not immediately seeing an issue – helion3 Commented Feb 6, 2014 at 4:34
It's just when I run it, the onload works. So my table is "invisible" but when click on my "Attack" button that's when the error es in. – user3268382 Commented Feb 6, 2014 at 4:39
i think the error is with document.getElementById("message").innerHTML=""; – amudhan3093 Commented Feb 6, 2014 at 4:42
element 'message' is missing in your code – Sam1604 Commented Feb 6, 2014 at 4:47
It is in there. It's right under body. – user3268382 Commented Feb 6, 2014 at 4:49

| Show 1 more ment

4 Answers 4

Sorted by: Reset to default 0

Demo FIDDLE

HTML

     <body onload="disappear()">
    <table border="1" >
        <tr>
            <td><img id="SHP" src="Hp/HPSlayerzach/hp2.png"/></td>
            <td></td>
            <td><img src="characters/slayerzach/slayerzach.png"/></td>
        </tr>
        <tr>
            <td><p id="demo"></p></td>
            <td ><img id="att" src="backgrounds/spacer1.png"/></td>
            <td></td>
        </tr>
        <tr>
            <td><img align="right" src="characters/fighterdan13/fighterDan13.gif"/></td>
            <td></td>
            <td><img id="FHP" src="hp/HPFighterdan13/hp1.png"/></td>
        </tr>
        <tr>
            <td colspan="2" background="backgrounds/backgroundText.png">
                <center><table border="0" id="list">
                    <tr>
                        <td style="font-family:verdana;font-size:15px"><center><a onclick="fire()">FIRE</a></center></td>
                        <td style="font-family:verdana;font-size:15px"><center>LIGHTNING</center></td>
                    </tr>
                    <tr>
                        <td style="font-family:verdana;font-size:15px"><center>WATER</center></td>
                        <td style="font-family:verdana;font-size:15px"><center>EARTH</center></td>
                    </tr>
                </table></center>
                <div id="message"></div>
            </td>
            <td>
                <center><table border="0" background="backgrounds/backgroundmenu.png">
                    <tr>
                        <td><button id="butAtt" onclick="attack()">Attack</button></td>
                        <td><button id="butItems" disabled>Items</button></td>
                    </tr>
                    <tr>
                        <td colspan="2"><center><button id="butRun" style="width:110px; height:25px;" disabled>Run</button><center></td>
                    </tr>
                </table></center>
            </td>
        </tr>
    </table>      
</body>

CODE

    function attack(){
        document.getElementById("list").style.display="block";
        document.getElementById("message").innerHTML="";
    }
    function fire(){    
        var y=document.getElementById("message");   
        var x=document.getElementById("demo");
        var z=document.getElementById("att");
        x.innerHTML=3;
   }
function disappear(){
    document.getElementById("list").style.display="none";   
    document.getElementById("message").innerHTML="<center>Wild SlayerZach has appeared.</center>";
}

Problem was you replace the message innerhtml on disappear.it remove the table which have id list.so i create div with id message inside the td and remove message id from the td.

The error is with 'document.getElementById("message").innerHTML="";'.There is no element by Id 'message'.Remove it,it works perfectly

The other best practice is to always check whether the element exists in the DOM:

something like below:

    if(document.getElementById("message")){ 
        document.getElementById("list").style.display="none";
document.getElementById("message").innerHTML="<center>Wild SlayerZach has appeared</center>";
    }

try dont use display:none through Javascript but from css, here is the example from your code i modify it a bit on link below

HTML Code

<body>
<td id="message" colspan="2" background="backgrounds/backgroundText.png" >
<table border="0" id="list" style="display:none;">
<tr>
   <td style="font-family:verdana;font-size:15px"><center><a onclick="fire()">FIRE</a></center></td>
   <td style="font-family:verdana;font-size:15px"><center>LIGHTNING</center></td>
</tr>
<tr>
    <td style="font-family:verdana;font-size:15px"><center>WATER</center></td>
    <td style="font-family:verdana;font-size:15px"><center>EARTH</center></td>
</tr>
</table>
<button id="butAtt" onclick="attack()">Attack</button>

Javascript

function attack(){
    document.getElementById("list").style.display="block";
    document.getElementById("message").innerHTML="";
}

jsfiddle

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javascript - Style.display blocknone problems - Stack Overflow

4 Answers 4

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