Simple Javascript question

When I click on the button, the first time, everything works fine, but the second time, nothing happens. Why is that?

<form name="alert"><input type="text" name="hour"><input type="text" name="min"><input type="button" value="ok" onclick="budilnik(this.form)">

<script type="text/javascript">
function budilnik(form)
{

budilnik=1;
min=form.min.value;
hour=form.hour.value;
alert (min+' '+hour+' '+budilnik);

}
</script>

---

Learn to use Firebug. It'll help you immensely in the future.

budilnik=1;

This may sound crazy, but this is redefining the function budilnik to an integer, which breaks your form's onlick. If you preface this statement with keyword var , you will shadow the function but not overwrite it. When you do not specify the var keyword, variables are assumed to be global scope, which can cause issues (like this).

I used firebug to see that on the second click, "budilnik is not defined." If you had used this tool, you could have probably debugged this issue yourself.

---

The variable budilnik is shadowing the function budilnik . Change the name of the variable, and your function should work right every time.

In more detail:

First, JavaScript sees budilink defined as a function. When budilnik is executed, the value of budilnik is overwritten with the integer 1. So the next time JavaScript is told to execute budilink , it tries to execute 1, instead of the function that was there before.

---

Put the var keyword before your variable name.

I've tested the following code and it just works:

<form name="alert">
<input type="text" name="hour">
<input type="text" name="min">
<input type="button" value="ok" onclick="budilnik(this.form);">

<script type="text/javascript">
function budilnik(form)
{
    var budilnik=1;
    var min=form.min.value;
    var hour=form.hour.value;
    alert (min+' '+hour+' '+budilnik); 
}
</script>

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