Javascript: how to check if the input is correct

Question

I know there is a way to make a field input and have user to type for example 'an apple' and then have javascript to check if the user typed in what I wanted which in this case is 'an apple' or if he/she typed in something else like 'a banana' and then if the answer was correct an information like 'correct' should appear and if it's not an information with 'wrong' should appear.

The question is how can I make it work?

I've searched the net for answers but it's giving me only how to check input length or something.

Can someone give me instructions or a link to a tutorial or something that would explain that, please.

Thank you.

Answer 1

try something like this

<input type="text" id="test">
<input type="button" value="click" onclick="z()"><span id="err"></span>

<script>
function z()
{
var a=document.getElementById("test");
if((a.value=="an apple")||(a.value=="apple"))
{
document.getElementById('err').innerHTML= 'correct';
}
else
{
document.getElementById('err').innerHTML= 'wrong';

}

}
</script>