console
function qaq(){
var q=document.getElementsByTagName("input")
var i;
for (i=0;i<q.length;i++){
q[i].value=" "
}
}
function qwq(){
var w=document.getElementById("one").value
document.getElementById("two").value=w*1000;
document.getElementById("three").value=w*100000;
document.getElementById("four").value=w*1000000;
}
function qeq(){
var e=document.getElementById("two").value
document.getElementById("one").value=e*0.001;
document.getElementById("three").value=e*100;
document.getElementById("four").value=e*1000;
}
function qrq(){
var r=document.getElementById("three").value
document.getElementById("one").value=r*0.00001;
document.getElementById("two").value=r*0.01;
document.getElementById("four").value=r*10
}
function qtq(){
var t=document.getElementById("four").value
document.getElementById("one").value=t*0.000001;
document.getElementById("two").value=t*0.001;
document.getElementById("three").value=t*0.1;
}
<html>
<head>
<title>长度转换单位</title>
</head>
<body>
<h1>长度转换单位</h1><br/>
<button onclick="qaq()">清空</button><br/>
<span>千米</span>
<input type="number" id="one" onchange="qwq()"></input><br/>
<span>米</span>
<input type="number" id="two" onchange="qeq()"></input><br/>
<span>厘米</span>
<input type="number" id="three" onchange="qrq()"></input><br/>
<span>毫米</span>
<input type="number" id="four" onchange="qtq()"></input>