请教一个获取输入值,并进行运算, 最后将值输入到输入框

Question

<script language="javascript">
var gb_flage=0;
function month_week(){
if (gb_flage>0)
question=confirm("确定要转换吗？")
else
question="1";if(question!="0"){
var rent=document.getElementById("rent").value;
document.getElementById("rent").value=rent*12/52;
document.getElementById("month_week").style.display='none';
document.getElementById("week_month").style.display='';
document.getElementById("a").innerText='周';
gb_flage=1;
}
}
function week_month(){
if (gb_flage>0)
question=confirm("确定要转换吗？")
else
question="1";if(question!="0"){
var rent=document.getElementById("rent").value;
document.getElementById("rent").value=rent*52/12;
document.getElementById("month_week").style.display='';
document.getElementById("week_month").style.display='none';
document.getElementById("a").innerText='月';
gb_flage=1;
}
}function gb(){
gb_flage=0;
}
</script>
<dt>租金：</dt><dd><input size="5" id="rent" name="rent" onchange="gb()" />/<label id="a">周</label>（可直接输入月租并点击<a href="javascript:void(0)" style="display:none" onclick="month_week()" id="month_week">将月租转换成周租</a><a href="javascript:void(0)" onclick="week_month()" id="week_month">将周租转换成月租</a>）
<dt>押金：</dt><dd><input size="5" id="deposit" /> 默认为一月租金

Answer 1

忘记计算租金了！！
<script language="javascript">
var gb_flage=0;
function month_week(){
if (gb_flage>0)
question=confirm("确定要转换吗？")
else
question="1";if(question!="0"){
var rent=document.getElementById("rent").value;
document.getElementById("rent").value=rent*12/52;
document.getElementById("month_week").style.display='none';
document.getElementById("week_month").style.display='';
document.getElementById("a").innerText='周';
zj();
gb_flage=1;
}
}
function week_month(){
if (gb_flage>0)
question=confirm("确定要转换吗？")
else
question="1";if(question!="0"){
var rent=document.getElementById("rent").value;
document.getElementById("rent").value=rent*52/12;
document.getElementById("month_week").style.display='';
document.getElementById("week_month").style.display='none';
document.getElementById("a").innerText='月';
zj();
gb_flage=1;
}
}function gb(){
gb_flage=0;
}
function zj(){
if (document.getElementById("month_week").style.display=='none')
document.getElementById("deposit").value=document.getElementById("rent").value*52/12;
else
document.getElementById("deposit").value=document.getElementById("rent").value;
}
</script>
<dt>租金：</dt><dd><input size="5" id="rent" name="rent" onchange="gb()" onblur="zj()" />/<label id="a">周</label>（可直接输入月租并点击<a href="javascript:void(0)" style="display:none" onclick="month_week()" id="month_week">将月租转换成周租</a><a href="javascript:void(0)" onclick="week_month()" id="week_month">将周租转换成月租</a>）
<dt>押金：</dt><dd><input size="5" id="deposit" /> 默认为一月租金