Question

154

Uncaught TypeError: Cannot read property 'value' of null, Element does exist

rated 0 times [ 160] [ 6] / answers: 1 / hits: 16620 / 9 Years ago, thu, september 24, 2015, 12:00:00

Before you downvote, I've read a lot of questions and it didn't help me.
My Javascript's alert returns null even when there is a value in the input type.

Here's the code :-

<script>

if (document.getElementById('p0002') != null) {

    var str = document.getElementById(p0002).value;

}

else {

    var str = null;

}

alert(str);

</script>



 <input type=hidden name=p0002 id=p0002 value=1 >

 <input type=hidden name=p0003 id=p0003 value=0 >

 <input type=hidden name=p0004 id=p0004 value=2 >

It always returns null. The error in console says :

Uncaught TypeError: Cannot read property 'value' of null

Trying to fix it since last 1 hour. What is wrong here?

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marcos

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4 Years ago

answered 9 Years ago isaacvalentinn · Accepted Answer

Wrap your JavaScript in window.onload. Currently your JavaScript is executing before the element exists:

<script>

window.onload = function () {

    if (document.getElementById('p0002') != null) {

        var str = document.getElementById(p0002).value;

    }

    else {

        var str = null;

    }

    alert(str);

}

</script>

Another thing you can do is move the script tag to be after the elements you're referencing:

<input type=hidden name=p0002 id=p0002 value=1 >

<input type=hidden name=p0003 id=p0003 value=0 >

<input type=hidden name=p0004 id=p0004 value=2 >

<script>

if (document.getElementById('p0002') != null) {

    var str = document.getElementById(p0002).value;

}

else {

    var str = null;

}

alert(str);

</script>