About Digital Clock Alarm Clock

The source code below is a digital alarm clock, but I have a question.

In the javascript of the clock, "check time" says "flg=-1", but "flg=1" and "flg=0" in "function changeFlg(){}", so if this number (-1) is "zero and non-one", all computers will function normally.
Is it acceptable to change numbers arbitrarily like this?

Also, no sound is set.

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML>
<HEAD>
<META http-equiv="Content-Type" content="text/html; charset=shift_jis"> 
<meta http-equiv="Content-Style-Type" content="text/css">
<meta http-equiv="Content-Script-Type" content="text/javascript">

<bgsound id="bgm" src="222.mid"loop="-1">

<TITLE> Digital alarm sound</TITLE> 


<!--- Clock JavaScript---> 
<SCRIPT type="text/javascript">
<!--
// Initialize the alarm flag.
varflg = 0;

// Time update & alarm check function
function timeCheck(){
    // Get the time.
    Now = new Date();
    Hour=Now.getHours();
    Min = Now.getMinutes();
    Sec = Now.getSeconds();

   // If "minutes" and "seconds" are single digits, mark them as two digits with a zero at the beginning.
        if(Hour<=9){ 
                       Hour="\u0020" + Hour; 
　　　}        
　　　　if(Min<=9){ 
                       Min = "0" + Min; 
　　　}
        if(Sec<=9){ 
                       Sec = "0" + Sec; 
　　　}


    // Displays the time.
    document.sampleForm.dspTime.value=Hour+":"+Min+":"+Sec;



    // Check the time.

if((flg==1)&(document.sampleForm.alarmH.value==Hour)&(document.sampleForm.alarmM.value==Min)){
document.getElementById('bgCol') .value = "333.wav", selectBgm( document.getElementById('bgCol')),
a number other than flg=-1;//0 and 1
　　　}
　}

// Alarm flag change function

function changeFlg(){
    if(flg==0){
    // Alarm not set,  
　　　　　　　　document.sampleForm.setAlarm.value="alarmOFF";
                document.getElementById("bgCol").value="";
　　　　　　　　selectBgm( document.getElementById('bgCol'));
      　　　　  flg = 1;
    } else {
    // When the alarm is set,
        document.sampleForm.setAlarm.value="alarm ON";
                document.getElementById("bgms").reset();
                selectBgm( document.getElementById('bgCol'));
　　　　　　    flg = 0;
  　}
}

　　// Set the following updates:
      setInterval (timeCheck, 100);
              window.onload=timeCheck;
// -- >
</SCRIPT>

<script type="text/javascript">
 <!--
   function selectBgm(e){
    var selectedIndex=e.selectedIndex;
        document.getElementById("bgCol").style.background=e [selectedIndex].style.backgroundColor;
        bgm.src=e [selectedIndex].value; 
        document.getElementById("bgCol").value=e[selectedIndex].value;
}

 // -- >
</script>
</head>


<BODY color="gold" bgcolor="black">

    <form id="bgms" style="text-align:right">
       <SELECT id="bgCol" onchange="selectBgm(this);">
         <OPTION value="">Music selection (stop)</OPTION>
         <OPTION value="222.mid" selected> Classic</OPTION>
         <OPTION value="333.wav">Alarm tone</OPTION>
       </SELECT>
    </form>

　　<FORM NAME="sampleForm" style="text-align:center">
　    <INPUT type="text" size=7NAME="dspTime">
<br>br>
<br>br>
　<div>
<INPUT type="text" name="alarmH" size=2 value="00">
<INPUT type="text" name="alarmM" size=2 value="00">
<INPUT type="button" id="setAlarm" name="setAlarm" value="alarm ON" onClick="changeFlg();">
　</div>
　　</FORM>

　</BODY>
</HTML>

javascript

2022-09-30 21:15

1 Answers

By design, it is desirable not to approve.

For the above clock, the variable "flg" is
　flg = 0 ... Alarm not set (initial value)
　flg=1...alarm configuration state
It can be read that it exists to keep the alarm ON/OFF.

If you set the variable "flg" to -1,

Turn off the alarm after it has occurred to prevent it from ringing again and again.
It can be read as if it were for the .
If so, it is desirable to set the alarm to "flg=0" without setting according to the above setting.
Configuring an out-of-design value of "flg=-1" causes confusion.
Confusion is the source of the defect.

This source code looks like a "flg=1 and other" design.
You just use "0" as the "other" value, and anything but "1".
It is not desirable to use floating values that are undefined by design.

*Why is the name of the audio file to be played bgCol?

2022-09-30 21:15

If you have any answers or tips

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