lovecoding
/
J250913


			
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							<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>

</body>
<script>
  /**
   * == 和 === 区别
   * == 只会比较两个值是否相同
   * === 不仅会比较值是否相同还会比较类型
   */
  var a = 10;
  var b = "10";
  console.log(a==b)    // true    相当于java 当中equlas 比较
  console.log(a===b)   // false   相当于java 当中==


  if (0){
    console.log("条件成立")
  }else{
    console.log("条件不成立")
  }

  if (null){
    console.log("条件成立")
  }else{
    console.log("条件不成立")
  }

  if (NaN){
    console.log("条件成立")
  }else{
    console.log("条件不成立")
  }

  if (""){
    console.log("条件成立")
  }else{
    console.log("条件不成立")
  }

  if (undefined){
    console.log("条件成立")
  }else{
    console.log("条件不成立")
  }


  var c = "111";
  var d = "abc11"
  console.log(typeof c)
  console.log(typeof parseInt(c))
  // Nan
  // console.log(parseInt(d))
  // console.log(typeof parseInt(d));

</script>
</html>