# Short circuit in JavaScript | Example code

There are 2 Short Circuit Conditionals in JavaScript first using `&&` (And logic) and another one is Evaluation with `||` (OR logic).

Logical AND (&&)

The logical AND (`&&`) operator (logical conjunction) for a set of boolean operands will be `true` if and only if all the operands are `true`. Otherwise, it will be `false`.

``expr1 && expr2``

Logical OR (||)

The logical OR (`||`) operator (logical disjunction) for a set of operands is true if and only if one or more of its operands is true. I

``expr1 || expr2``

## Short circuit in JavaScript

A simple example code is evaluating an AND expression (&&), if the first operand is false, JavaScript will short-circuit and not even look at the second operand.

``````true && true
// true

true && false
// false

false && false
// false``````

Code

``````<!DOCTYPE html>
<html>
<body>

<script>
const a = 3;
const b = -2;

console.log(a > 0 && b > 0);
</script>

</body>
</html
>``````

Output:

Expressions – Logical OR

``````const a = 3;
const b = -2;

console.log(a > 0 || b > 0);
// expected output: true``````

### Does JavaScript have a “Short-circuit” evaluation?

Answer: Yes, JavaScript has a “short-circuit” evaluation like && Operator in C#.

• `(some falsy expression) && expr` will evaluate to falsy expression
• `(some truthy expression) || expr` will evaluate to a truthy expression
``````if (true == true || foo.foo){
// Passes, no errors because foo isn't defined.
}``````

Do comment if you have any doubts or suggestions on this JS short circuit topic.

Note: The All JS Examples codes are tested on the Firefox browser and the Chrome browser.

OS: Windows 10

Code: HTML 5 Version

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