Example of initial values of Boolean objects in js

Source: Internet
Author: User

A Boolean (logical) object is used to convert non-logical values to logical values (true or false ).
Create a Boolean object

Use the keyword new to define a Boolean object. The following code defines a logical object named myBoolean:

Var myBoolean = new Boolean ()

Note: If the logical object has no initial value or its value is 0,-0, null, "", false, undefined, Or NaN, the object value is false. Otherwise, the value is true (even when the independent variable is string "false )!

All the following code lines will create a Boolean object whose initial value is false.
Copy codeThe Code is as follows:
<Script type = "text/javascript">
Var myBoolean = new Boolean ();
Document. write (myBoolean );
Document. write ("<br/> ");

Var myBoolean = new Boolean (0 );
Document. write (myBoolean );
Document. write ("<br/> ");

Var myBoolean = new Boolean (null );
Document. write (myBoolean );
Document. write ("<br/> ");

Var myBoolean = new Boolean ("");
Document. write (myBoolean );
Document. write ("<br/> ");

Var myBoolean = new Boolean (false );
Document. write (myBoolean );
Document. write ("<br/> ");

Var myBoolean = new Boolean (NaN );
Document. write (myBoolean );
Document. write ("<br/> ");
</Script>

Running result:

False
False
False
False
False
False

All the following code lines will create a Boolean object whose initial value is true:
Copy codeThe Code is as follows:
<Script type = "text/javascript">
Var myBoolean = new Boolean (1 );
Document. write (myBoolean );
Document. write ("<br/> ");

Var myBoolean = new Boolean (true );
Document. write (myBoolean );
Document. write ("<br/> ");

Var myBoolean = new Boolean ("true ");
Document. write (myBoolean );
Document. write ("<br/> ");

Var myBoolean = new Boolean ("false ");
Document. write (myBoolean );
Document. write ("<br/> ");

Var myBoolean = new Boolean ("Bill Gates ");
Document. write (myBoolean );
Document. write ("<br/> ");
</Script>

Running result:

True
True
True
True
True
This initial value is different from that of java and c. You should pay attention to it later!

Related Article

Contact Us

The content source of this page is from Internet, which doesn't represent Alibaba Cloud's opinion; products and services mentioned on that page don't have any relationship with Alibaba Cloud. If the content of the page makes you feel confusing, please write us an email, we will handle the problem within 5 days after receiving your email.

If you find any instances of plagiarism from the community, please send an email to: info-contact@alibabacloud.com and provide relevant evidence. A staff member will contact you within 5 working days.

A Free Trial That Lets You Build Big!

Start building with 50+ products and up to 12 months usage for Elastic Compute Service

  • Sales Support

    1 on 1 presale consultation

  • After-Sales Support

    24/7 Technical Support 6 Free Tickets per Quarter Faster Response

  • Alibaba Cloud offers highly flexible support services tailored to meet your exact needs.