How JavaScript converts non-logical values to logical values

This article mainly introduces how JavaScript converts non-logical values into logical values, which has a certain reference value, and interested friends can refer to it. I hope you can learn a lot after reading this article.

JavaScript Boolean object

Boolean (logical) objects are used to convert non-logical values into logical values (true or false).

You can think of a Boolean object as an object wrapper that produces logical values.

Create a Boolean object

Use the keyword new to define the Boolean object. A logical object named myBoolean is defined below:

Var myBoolean=new Boolean ()

If the logical object has no initial value or its value is 0,-0, null, "", false, undefined, or NaN

Then the value of the object is false. Otherwise, the value is true (even when the argument is the string "false")!

All of the following lines of code create a Boolean object with an initial value of false.

Var myBoolean=new Boolean (); var myBoolean=new Boolean (0); var myBoolean=new Boolean (null); var myBoolean=new Boolean (""); var myBoolean=new Boolean (false); var myBoolean=new Boolean (NaN)

All of the following lines of code create a Boolean object with an initial value of true:

Var myBoolean=new Boolean (1); [xss_clean] (myBoolean); [xss_clean] ("); var myBoolean=new Boolean (true); [xss_clean] (myBoolean); [xss_clean] ("); var myBoolean=new Boolean ("true"); [xss_clean] (myBoolean); [xss_clean] ("); var myBoolean=new Boolean (" false "); [xss_clean] (myBoolean) [xss_clean] ("); var myBoolean=new Boolean (" Bill Gates "); [xss_clean] (myBoolean); [xss_clean] (")

Check whether the logical object is true or false:

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") [xss_clean] ("0 is logical" + b1 + ") [xss_clean] (" 1 is logical "+ b2 +") [xss_clean] ("empty string is logical" + b3 + "") [xss_clean] ("null is logical" + b4 + ") [xss_clean] (" NaN is logical "+ b5 +") [xss_clean] ("string" false "is logical" + b6 + "")

Properties and description of Boolean object

Constructor: returns a reference to the Boolean function that created this object

Prototype: gives you the ability to add properties and methods to objects.

Boolean object method and description

ToSource (): returns the source code of the object.

ToString (): converts a logical value to a string and returns the result.

ValueOf (): returns the original value of the Boolean object.

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