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Editorial Team
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Asked: 2026-06-15T23:26:43+00:00

I am beginner in javascript. js file var msgErrorPalletizedWeight = document.getElementById(‘msgError’); function palletizedWeightValidation() {

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I am beginner in javascript.

js file

         var msgErrorPalletizedWeight = document.getElementById('msgError');
         function palletizedWeightValidation() {
              console.log("hello");
/*ERROR*/     msgErrorPalletizedWeight.innerHTML += ("Please enter all the values marked with *");
         }

HTML

<head runat="server">
   <title></title>
   <link href="Styles/Site.css" rel="stylesheet" type="text/css" />
   <script src="Scripts/file.js" type="text/javascript"></script>
</head>
<body>
    <p id="msgError"></p>
    <asp:Button ID="btnSubmitPalletized" runat="server" Text="Submit" 
                   OnClientClick="palletizedWeightValidation()" />
</body>

ERROR

Cannot read property ‘innerHTML’ of null

I searched many sites before asking here, they all recommending to check for null before validations which I can do but my problem here is I want to add some text to the p tag as you can see.. How to achieve that? I even tried appending, thought it might solve the problem. I know this is a silly mistake because there are many posts on this… the thing is that I cant understand where I am going wrong.

Please help.

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1 Answer

  1. Editorial Team

    You are trying to access the element of html when it is not ready, put the statement in event function to get the element in function palletizedWeightValidation. 

          function palletizedWeightValidation() {
              var msgErrorPalletizedWeight = document.getElementById('msgError');
              console.log("hello");
/*ERROR*/     msgErrorPalletizedWeight.innerHTML += ("Please enter all the values marked ith *");
         }

    EDIT To stop postback, you need to return false from javascrip function.

     <asp:Button ID="btnSubmitPalletized" runat="server" Text="Submit" 
                   OnClientClick="return palletizedWeightValidation()" />


      function palletizedWeightValidation() {
              var msgErrorPalletizedWeight = document.getElementById('msgError');
              console.log("hello");
/*ERROR*/     msgErrorPalletizedWeight.innerHTML += ("Please enter all the values marked ith *");
              return false; // returning true will cause postback.
         }
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