Java-Script

　花火もどき－２ 　　　　　
Sample
ソース
<HTML><HEAD>
<TITLE>Java-Script</TITLE>
<SCRIPT LANGUAGE="JavaScript">
<!-- 
var xpos0=0;var ypos0=0;
n=30;
var _width = 800;
var _height = 800;
_width = screen.width*4/6*Math.random();
_height= screen.height*3/6*Math.random();
xpos0 = _width+5; 
ypos0 =  _height-3; 
xpos=new Array();
ypos=new Array();
i=new Array();
l=new Array();
dot=new Array();
thisl=new Array();
var this1;
var this2;
var this3;
var thisol1;
var thisol2;
var thisol3;
var thisol4;
var thisol5;
for (m=1;m<(n+1);m++){
  xpos[m] = _width+10*Math.random(); 
  ypos[m] = _height-10*Math.random();
  this1=Math.round(255*Math.random());
  this2=Math.round(255*Math.random());
  this3=Math.round(255*Math.random());
  thisol1=this1.toString(16);
  thisol2=this2.toString(16);
  thisol3=this3.toString(16);
  thisol4=thisol1+thisol2+thisol3;
  thisol5=eval("thisol4");
  thisl[m] =thisol5; 
  i[m]=xpos[m]-xpos0;
  l[m]=ypos[m]-ypos0;
}
var p=0;
timeID=0;
function hanabi() {
  p=p+1;
  for (m=1;m<(n+1);m++){
    document.all["dot["+m+"]"].style.pixelTop = ypos[m];
    document.all["dot["+m+"]"].style.pixelLeft = xpos[m];
    xpos[m]=xpos[m]+i[m];
    ypos[m]=ypos[m]+l[m];
    l[m]=l[m]+0.2;
    if ((xpos[m]<=5)||(ypos[m]<=5)){
      xpos[m] = _width+10*Math.random(); 
      ypos[m] = _height-10*Math.random();
      i[m]=xpos[m]-xpos0;
      l[m]=ypos[m]-ypos0;
    }
    else if ((xpos[m]>=screen.width*8/10)||(ypos[m]>=screen.height*7/10)){
      xpos[m] = _width+10*Math.random(); 
      ypos[m] = _height-10*Math.random();
      i[m]=xpos[m]-xpos0;
      l[m]=ypos[m]-ypos0;
    }
  }

  if (p>40){
    _width = screen.width*4/6*Math.random();
    _height= screen.height*3/6*Math.random();
    xpos0 = _width+5; 
    ypos0 = _height-3;
    p=0;
    for (m=1;m<(n+1);m++){
      xpos[m] = _width+10*Math.random(); 
      ypos[m] = _height-10*Math.random();
      this1=Math.round(255*Math.random());
      this2=Math.round(255*Math.random());
      this3=Math.round(255*Math.random());
      thisol1=this1.toString(16);
      thisol2=this2.toString(16);
      thisol3=this3.toString(16);
      thisol4=thisol1+thisol2+thisol3;
      thisol5=eval("thisol4");
      thisl[m] =thisol5; 
      i[m]=xpos[m]-xpos0;
      l[m]=ypos[m]-ypos0;
    }
  }
  timeID=setTimeout("hanabi()",1);
}
//-->
</SCRIPT>
</HEAD>
<body bgcolor=black onLoad="hanabi()">
<SCRIPT LANGUAGE="JavaScript">
<!--
for (m=1;m<(n+1);m++){
  document.write("<div id=\"dot["+ m +"]\" style=\"POSITION: absolute; Z-INDEX: "
+ m +" VISIBILITY: visible; TOP: 15px; LEFT: 15px; width:1;\"><font color=#"
+thisl[m]+"size=1>★</font></div>");
}
//-->
</SCRIPT>
<FORM>
<INPUT TYPE=button VALUE="ウインドウを閉じる" onClick=window.close()>
</FORM>
</BODY>
</HTML>
ワンポイント解説
_width = screen.width*4/6*Math.random();
_height= screen.height*3/6*Math.random();
で、開始位置をランダムに設定しています。