TypeScript Logical Operators

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

Operator Description

Operator	Description
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

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

Drop me your questions in comments section.

Happy Learning !!

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TypeScript Logical Operators

Logical Operators

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