Her defasında farklı bir resim

<SCRIPT LANGUAGE="JavaScript"> 

today=new Date(); 
jran=today.getTime(); 

function rnd() { 

ia=9301; 
ic=49297; 
im=233280; 

jran = (jran*ia+ic) % im; 
return jran/(im*1.0); 
}; 

function rand(number) { 

return Math.ceil(rnd()*number); 
}; 

document.write("<CENTER>"); 
for(i=1;i<=1;i++) { 
myNum=(rand(12)); 
if(myNum == 1) document.write("<img src='header1.jpg'>");   
if(myNum == 2) document.write("<img src='header2.jpg'>"); 
if(myNum == 3) document.write("<img src='header3.jpg'>"); 
if(myNum == 4) document.write("<img src='header4.jpg'>"); 
if(myNum == 5) document.write("<img src='header1.jpg'>"); 
if(myNum == 6) document.write("<img src='header2.jpg'>"); 
if(myNum == 7) document.write("<img src='header3.jpg'>"); 
if(myNum == 8) document.write("<img src='header4.jpg'>"); 
if(myNum == 9) document.write("<img src='header1.jpg'>"); 
if(myNum == 10) document.write("<img src='header2.jpg'>"); 
if(myNum == 11) document.write("<img src='header3.jpg'>"); 
if(myNum == 12) document.write("<img src='header4.jpg'>"); 
else { 
document.write(); 
} 

}; 

document.write("</CENTER>"); 

</SCRIPT>   

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