console 命令行工具 X clear

console

//清除所有的数字
function  cut(){
    var x=document.getElementsByTagName("input")
    var i;
   for(i=0;i<x.length;i++){
  x[i].value=""
 }
}
//当用户输入第一个文本的内容时，输出其他三个文本的值
function  kilometer(){
    var t=document.getElementById("num").value
  document.getElementById("num1").value = t*1000;
  document.getElementById("num2").value =t*100000;
  document.getElementById("num3").value = t*1000000;
}

/* meter to others */
//当用户输入第二个文本的内容时，输出其他三个文本的值
function  meter(){
    var m=document.getElementById("num1").value
  document.getElementById("num").value = m*0.001;
  document.getElementById("num2").value =m*100;
  document.getElementById("num3").value = m*1000;
}
//当用户输入第三个文本的内容时，输出其他三个文本的值
/* centimeter to others */
function  centimeter(){
    var n=document.getElementById("num2").value
  document.getElementById("num").value = n*0.00001.toFixed(5);
  document.getElementById("num1").value = n*0.01.toFixed(5);
  document.getElementById("num3").value = n*10;
}
//当用户输入第四个文本的内容时，输出其他三个文本的值
/* millimeter to others */
function  millimeter(){
    var b=document.getElementById("num3").value
  document.getElementById("num").value = b*0.000001.toFixed(6);
  document.getElementById("num1").value = b*0.001.toFixed(6);
  document.getElementById("num2").value = b*0.1.toFixed(6);
}

<html>
<head><title>单位转换</title></head>
<body>
    <div style="margin-left:300px;" >
	<h2>长度转换单位</h2>
  <button  onclick="cut()">清空</button>
  <br/>  
   <span>千米:</span>
   <input type="number"  id="num"  onchange="kilometer()">
   <br/>
    <span>&nbsp;&nbsp米:</span>
   <input type="number"  id="num1"  onchange="meter()">
    <br/>
     <span>厘米:</span>
   <input type="number"  id="num2"   onchange="centimeter()">
    <br/>
 <span>毫米:</span>
   <input type="number"  id="num3"  onchange="millimeter()">
    <br/>

</div>

</body>

</html>