Below is the example of JavaScript Boolean method.
- Example:
<script>
function
gfg() {
document.write(Boolean(12));
}
gfg();
</script>
chevron_rightfilter_none - Output:
true
Boolean is a datatype that returns either of two values i.e. true or false. In JavaScript, Boolean is used as a function to get the value of a variable, object, conditions, expressions, etc. in terms of true or false.
Example:
Here a1 and a2 stores the boolean value i.e. true and false respectively.
var a1 = true; var a2 = false;
Note: Below variables are initialized with strings not boolean values.
var a1 ="true"; var a2 ="false";
Boolean() function in JavaScript: Boolean function returns the boolean value of variable. It can also be used to find boolean result of a condition, expression etc.
Syntax:
Boolean(variable/expression)
Note: A variable or object which has value are treated as true boolean values. ‘0’, ‘NaN’, empty string, ‘undefined’, ‘null’ are treated as false boolean values.
Code #1:
Below program will give true values as output.
<!DOCTYPE html> <html> <body> <script> document.write( 'Boolean(10) is ' + Boolean(10)); document.write( '<br>' ); document.write( 'Boolean("GeeksforGeeks") is ' + Boolean( "GeeksforGeeks" )); document.write( '<br>' ); document.write( 'Boolean(2.74) is ' + Boolean(2.74)); document.write( '<br>' ); document.write( 'Boolean(-1) is ' + Boolean(-1)); document.write( '<br>' ); document.write( "Boolean('true') is " + Boolean( 'true' )); document.write( '<br>' ); document.write( "Boolean('false') is " + Boolean( 'false' )); document.write( '<br>' ); document.write( 'Boolean(3 * 2 + 1.11) is ' + Boolean(3 * 2 + 1.11)); document.write( '<br>' ); document.write( 'Boolean(1<2) is ' + Boolean(1 < 2)); </script> </body> </html> |
Output:
Boolean(10) is true Boolean("GeeksforGeeks") is true Boolean(2.74) is true Boolean(-1) is true Boolean('true') is true Boolean('false') is true Boolean(3 * 2 + 1.11) is true Boolean(1<2) is true
Code #2:
Below program will give false values as output.
<!DOCTYPE html> <html> <body> <script> var e; //undefined document.write( 'Boolean(0) is ' + Boolean(0)); document.write( '<br>' ); document.write( 'Boolean("") is ' + Boolean( "" )); document.write( '<br>' ); document.write( 'Boolean(e) undefined is ' + Boolean(e)); document.write( '<br>' ); document.write( 'Boolean(-0) is ' + Boolean(-0)); document.write( '<br>' ); document.write( 'Boolean(false) is ' + Boolean( false )); document.write( '<br>' ); document.write( 'Boolean(NaN) is ' + Boolean(NaN)); document.write( '<br>' ); document.write( 'Boolean(null) is ' + Boolean( null )); document.write( '<br>' ); document.write( 'Boolean(1>2) is ' + Boolean(1 > 2)); </script> </body> </html> |
Output:
Boolean(0) is false Boolean("") is false Boolean(e) undefined is false Boolean(-0) is false Boolean(false) is false Boolean(NaN) is false Boolean(null) is false Boolean(1>2) is false
JavaScript Boolean object:
The boolean object in javascript is an object wrapper for boolean values. Booleans in JavaScript can also be defined using the new keyword.
Syntax:
new Boolean(value)
Code #3:
<!DOCTYPE html> <html> <body> <script> var v1 = false ; var v2 = new Boolean( false ); var v3 = new Boolean( "" ); var v4 = new Boolean(0); var v5 = new Boolean( true ); var v6 = new Boolean( "GeeksforGeeks" ); document.write( 'v1 = ' + v1); document.write( "<br>" ); document.write( 'v2 = ' + v2); document.write( "<br>" ); document.write( 'v3 = ' + v3); document.write( "<br>" ); document.write( 'v4 = ' + v4); document.write( "<br>" ); document.write( 'v5 = ' + v5); document.write( "<br>" ); document.write( 'v6 = ' + v6); </script> </body> </html> |
Output:
v1 = false v2 = false v3 = false v4 = false v5 = true v6 = true
Code #4:
<!DOCTYPE html> <html> <body> <script> var v1 = true ; var v2 = new Boolean( true ); document.write( 'v1 = = v2 is ' + (v1 == v2)); document.write( "<br>" ); document.write( 'v1 = = = v2 is ' + (v1 === v2)); </script> </body> </html> |
Output:
v1 = = v2 is true v1 = = = v2 is false
Note: v1 = = = v2 is not true as the type of v1 and v2(object) is not same.
Supported Browsers:
- Google Chrome
- Internet Explorer
- Firefox
- Apple Safari
- Opera