JAVASCRIPT BASICS
- Introduction to JavaScript
- Javascript Features
- JavaScript in HTML
- JavaScript Syntax
- Output in JavaScript
- JavaScript Variables
- Javascript let Keyword
- JS Literals and Keywords
- JavaScript Data Types
- JavaScript Operators
- JavaScript Events
- Javascript const Keyword
JAVASCRIPT FLOW CONTROL AND LOOPS
- JS if, else and else if
- JavaScript for Loop
- JS while and do-while loop
- JS Switch case
- JS break and continue
JAVASCRIPT ADVANCED
- JavaScript Strings
- JavaScript String Methods
- JavaScript Array
- JavaScript Regular Expression
- JavaScript Popup Boxes
- JavaScript Functions
- JavaScript Default Parameters
- JavaScript Rest Parameters
- JavaScript Arrow Function
- JavaScript Errors
- JavaScript Error Handling
- JavaScript Cookies
JAVASCRIPT OBJECT
- JavaScript Objects
- JavaScript User-defined Object
- JavaScript Boolean Object
- JavaScript Number Object
- JavaScript Math Object
- JavaScript Date Object
- JavaScript RegExp Object
JAVASCRIPT WEB API AND INTERFACES
JavaScript Boolean object is a member of global objects and a wrapper class. It is used to create a boolean object which holds true or false value, depending upon the value used while creating the Boolean object.
The Boolean object’s true and false values are different from the primitive boolean type’s true and false values.
As already mentioned, it has two values, true and false. The Boolean object returns false when it is passed with values such as 0, -0, an empty string(""), false, null, undefined, or Not a Number(NaN) while creating the Boolean object. Apart from all these values which set the initial value as false for the Boolean object, all other values, even an empty array([]), empty object({}) or the string “false“, will set the initial value for the Boolean object as true.
Creating JavaScript Boolean Object
To create an instance of the Boolean object, we use the new keyword with the Boolean object constructor function, providing a value at the time of creation.
Following is the syntax for it:
let bool = new Boolean(SOME_VALUE);
Depending upon the value passed, the initial value is set as true or false.
Let’s take an example,
// Creating Boolean Object
let boolObj = new Boolean(true);
document.write(boolObj);
boolObj = new Boolean(false);
document.write("<br>"+boolObj);
true false
JavaScript Boolean Object False
JavaScript Boolean Object will have the initial value as false if the value provided at the time of object creation is 0, -0, NaN, null, undefined, false, empty string or even if no value is provided because the default value is also false.
let obj1 = new Boolean();
let obj2 = new Boolean(0);
let obj3 = new Boolean(null);
let obj4 = new Boolean('');
let obj5 = new Boolean(false);
document.write(obj1+" "+obj2+" "+obj3+" "+obj4+" "+obj5)
false false false false false
JavaScript Boolean Object True
Apart from the values specified above, for which the initial value of the Boolean object is false, all other values will set the value as true. Let’s take a few examples,
let obj1 = new Boolean(true);
let obj2 = new Boolean('true');
let obj3 = new Boolean('false');
let obj4 = new Boolean('hello');
let obj5 = new Boolean([]);
let obj6 = new Boolean({});
document.write(obj1+" "+obj2+" "+obj3+" "+obj4+" "+obj5+" "+obj6)
true true true true true true
JavaScript Boolean Object vs. Primitive Boolean type
As we have already mentioned that the boolean object and primitive boolean types are different. The Boolean object is a JavaScript object and not a primitive type, but an object type, which can have true or false as its value.
Let’s take an example, where we will see how the Boolean object and the primitive boolean type behave when used in a JavaScript conditional statement expression.
// Boolean object
let obj = new Boolean(false);
// using in if condition
if(obj)
{
document.write("It is boolean object"); // executes
}
// Primitive value
let bool = false;
if(bool)
{
document.write("It is primitive boolean"); // does not execute
}
It is boolean object
In spite of the false value of the Boolean object, the first if statement executes, that is because when we provide an object in the if condition, it is always evaluated as true.
We can get the value of the Boolean objects by using the valueOf() method of the Boolean object and then it will be treated as a norma primitive type true or false value.
Converting Boolean Object to Primitive
We can use the valueOf() method of the Boolean object for accessing its value,
// Boolean object
let obj = new Boolean(false);
// using the value of Boolean object in condition
if(obj.valueOf()){
document.write("It is boolean object"); // does not execute
}
else{
document.write("boolean value is false"); // executes
}
boolean value is false
Methods of Boolean Object
The following are some of the commonly used methods of the Boolean object.
toString():converts the boolean value into a string and returns the string.valueOf():returns the primitive value of a Boolean object.
JavaScript Boolean Object Example
Let’s see another code example for the Boolean object:
<html>
<head>
<title>
Using Boolean Object
</title>
</head>
<body>
<script type="text/javaScript">
let bool1 = new Boolean(0);
let bool2 = new Boolean(8);
let bool3 = new Boolean(2);
let bool4 = new Boolean("");
let bool5 = new Boolean("Hello");
let bool6 = new Boolean('false');
let bool7 = new Boolean(null);
let bool8 = new Boolean(NaN);
document.write("0 value is boolean :" + bool1+"<br>");
document.write("8 value is boolean :" + bool2+"<br>");
document.write("1 value is boolean :" + bool3+"<br>");
document.write("An empty string is boolean :" + bool4+"<br>");
document.write("String 'Hello' is boolean :" + bool5+"<br>");
document.write("String 'false' is boolean :" + bool6+"<br>");
document.write("null is boolean :" + bool7+"<br>");
document.write("NaN is boolean :" + bool8+"<br>");
</script>
</body>
</html>
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