javascript中“==”跟“===”区别

javascript中“==”和“===”区别
   最近看书突然发现有在js中有===用法，上网查资料发现三个等是精确比较的意思，不仅值相同，还要类型相同。不说废话，直接上代码。

<html>
 <head>
  <title> ===和==区别 </title>
  </head>

 <body>
  	<script type="text/javascript">
var y = 5; 
if(y == "5"){ 
document.write("== '5' true"); 
}  
else{ 
document.write("== '5' false "); 
} 
document.write("</br>");
if(y == 5){ 
document.write("== 5 数字 is true "); 
} 
else{ 
document.write("== 5  数字 false "); 

} 
document.write("</br>");
if( y === 5){ 
document.write("=== 数字5 is true "); 
} 
else{ 
document.write("=== 数字5 false "); 
} 
document.write("</br>");
if(y !== "5"){ 
document.write("!== '5' is true "); 
} 
else{ 
document.write("!== '5' is false"); 
} 
</script> 

 </body>
</html>