What is Logical AND (&&) in JavaScript?

The Logical AND in Javascript i.e represented by && is also called a logical operator that is used to combine multiple statements in the javascript, and returns true if all the statements satisfy the particular condition, otherwise returns false, if any statement fails to satisfy the condition.

Syntax of AND in Javascript

Let's understand the syntax of the Logical AND in javascript.

The logical AND in Javascript works on the two expressions and returns the boolean expression i.e true or false according to the set of instructions in the expression.

Short-circuit Evaluation

The Short-circuit evaluation is a programming concept in which the compiler skips the execution of the statements when the particular statements get false. The And operator in the javascript is also a short-circuit operator.

Let's understand this using an example.

The JavaScript compiler compiles the above statement in the javascript from left to right, when it finds the expression false it will immediately stop the compilations of the further statements. The "expression" will not be compiled by the compiler.

Example AND in Javascript

Let's understand the use of the AND in Javascript using an example.

In the below program, We are checking whether the number is even or not, for even the number must be greater than zero and divisible by 2, this condition is handled by the operator.

The output will be "The number is even", because both the condition that is number>=0 and number%2==0 are satisfied by the given number.

Output:

Operator Precedence

The AND in Javascript has the highest precedence over the OR operator in javascript. The precedence means the AND operator expression evaluates before the OR operator expression. You can learn more about Operator precedence in javascript at Scaler Topics.

Let's understand this using an example.

Output:

The output will be false because the expression (true||false) is evaluated after the false expression in the AND operator.

Using AND

Let's understand the use cases of AND Operator in javascript.

Output:

Conversion Rules for Booleans

Let's understand the rules of converting the logical operator AND to OR operator, and conversion OR operator to AND operator.

Converting AND to OR

The below expression is using the AND in the javascript.

Let's understand how to convert the above AND expression to OR operator expression. The above AND operator expression will be equal to the below OR operator expression.

Let's understand how to convert AND condition to the OR condition using an example

Output:

Converting OR to AND in Javascript

Let's understand how to convert OR operator expression to the AND operator expression.

Consider the below OR Operator Expression.

Let's understand how to convert the above OR operator expression to the AND operator expression.

Let's understand how to convert the OR condition to the AND Condition.

Output:

Removing Nested Parentheses

The logical operator such as an operator is evaluated from left to right that's why it is very easy to remove the extra parenthesis from the complex expression in order to solve properly.

Let's understand this using an example

expression1 || (expression2&& expression3)

The above expression can be changed to the below expression

expression1 || expression2&& expression3

Let's understand this using an example. In the below example, we are removing the extra parentheses that are used in the first expression.

Output:

Browser Compatibility

Browser compatibility of the AND operator.

See More

• Comparison Operators in JavaScript