教程·Javascript 中文手册
The Boolean object is an object wrapper for a boolean value.
| 实现版本 | Navigator 3.0, LiveWire 1.0 |
The Boolean constructor:
new Boolean(value)
| value | The initial value of the Boolean object. The value is converted to a boolean value, if necessary. If value is omitted or is 0, null, false, or the empty string (""), the object has an initial value of false. All other values, including the string "false", create an object with an initial value of true. |
Use a Boolean object when you need to convert a non-boolean value to a boolean value. You can use the Boolean object any place JavaScript expects a primitive boolean value. JavaScript returns the primitive value of the Boolean object by automatically invoking the valueOfmethod.
| Defines a 属性 that is shared by all Boolean objects. |
| Returns a string representing the specified object. |
The following示例 create Boolean objects with an initial value of false:
bNoParam = new Boolean()
bZero = new Boolean(0)
bNull = new Boolean(null)
bEmptyString = new Boolean("")
bfalse = new Boolean(false)
The following示例 create Boolean objects with an initial value of true:
btrue = new Boolean(true)
btrueString = new Boolean("true")
bfalseString = new Boolean("false")
bSuLin = new Boolean("Su Lin")
Represents the prototype for this class. You can use the prototype to add properties or methods to all instances of a class. For information on prototypes, see Function.prototype.
| Boolean | 实现版本 | Navigator 3.0, LiveWire 1.0 |
Returns a string representing the specified object.
| Boolean | 实现版本 | Navigator 3.0, LiveWire 1.0 |
toString()
无。
Every object has a toString method that is automatically called when it is to be represented as a text value or when an object is referred to in a string concatenation.
You can use toString within your own code to convert an object into a string, and you can create your own function to be called in place of the default toString method.
For flag = new Boolean(true)
document.write("flag.toString() is " + flag.toString() + "<BR>")
For information on defining your own toString method, see the Object.toStringmethod.