HowToDoInJava

TypeScript Logical Operators

By | Filed Under: TypeScript

TypeScript logical operators are similar what you learn in JavaScript logical operators. These operators help in comparing boolean expressions and producing single boolean value as result.

Logical Operators

OperatorDescription
Logical AND operator – && If both operands (or expressions) are true, then result will be true, else false.

			let firstVar = true;
			let secondVar = false;

			console.log( firstVar && secondVar );	//false
			console.log( firstVar && true );		//true
			console.log( firstVar && 10 );			//10 which is also 'true'
			console.log( firstVar && '10' );		//'10'	which is also 'true'

Read More: Truthy and Falsy

Logical OR operator – || If any of the two operands (or expressions) are true, then result will be true, else false.

			let firstVar = true;
			let secondVar = false;

			console.log( firstVar || secondVar );	//true
			console.log( firstVar || true );		//true
			console.log( firstVar || 10 );			//true
			console.log( firstVar || '10' );		//true
Logical NOT operator – ! It is used to reverse the logical state of its operand. It converts true to false, and vice-versa.

			let firstVar = 10;
			let secondVar = 20;

			console.log( !true );		//false
			console.log( !false );		//true
			console.log( !firstVar );	//false
			console.log( !null );		//true

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