JavaScript Boolean Object 逻辑

Create a Boolean Object

The Boolean object represents two values: "true" or "false".

The following code creates a Boolean object called myBoolean:

var myBoolean=new Boolean();

If the Boolean object has no initial value, or if the passed value is one of the following:

  • 0
  • -0
  • null
  • ""
  • false
  • undefined
  • NaN

the object is set to false. For any other value it is set to true (even with the string "false")!


<!DOCTYPE html>

var b1=new Boolean(0);
var b2=new Boolean(1);
var b3=new Boolean("");
var b4=new Boolean(null);
var b5=new Boolean(NaN);
var b6=new Boolean("false");

document.write("0 is boolean "+ b1 +"<br>");
document.write("1 is boolean "+ b2 +"<br>");
document.write("An empty string is boolean "+ b3 + "<br>");
document.write("null is boolean "+ b4+ "<br>");
document.write("NaN is boolean "+ b5 +"<br>");
document.write("The string 'false' is boolean "+ b6 +"<br>");