Commonly, **logical operators** are used to combine two boolean values. But the truth is that we can do a lot more with the `AND` and `OR` operators. 

>In JavaScript, **short-circuiting** is the evaluation of an expression from left to right with  `||` and `&&` operators.

>If the condition is *met* and the rest of the conditions *won’t affect* the already evaluated result, the expression will *short-circuit* and return that result (value).

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## Short-circuiting with the or (||) operator

The **`||` operator** will return the first truthy value of all the operands, or simply the last value if all of them are falsy.



## Code

What do you think the result of this one will be? Run the code to check.


console.log(3 || 'Orange');
console.log('' || 'Orange');
console.log(true || 0);
console.log(undefined || null);

codemirror

console

## Explanation

In the example below we want to check if the object `person` contains the `job` key. To do this, we simply `console.log` the value of person  or for `person.job` we use  `OR` to get the default string of `unemployed`. 

var person = {
  name: 'Jack',
  age: 34
}
console.log(person.job || 'unemployed');
// 'unemployed'

Since `person.job` doesn’t exist, we get `undefined`. Since undefined is a falsy value, JavaScript will instead go to the other side of the `||` and accept whatever value is there.

## Short-circuiting with the and (&&) operator

The `&&` operator will return false as soon as it gets any falsy value and will return the last true value if all the values are truthy.

## Code

Now try to predict the result of this code. Run it to check.

console.log(0 && 'Orange');
console.log('' && 'Orange');
console.log(true && null);
console.log('Apple' && 'Orange');

## Explanation

It’s possible to take advantage of short-circuiting and to shorten, or even avoid, the `if` statement.

In the example below, we want to check if an object `person` key `age` value is higher than 18. And if yes, we state that this person is allowed to drive.

var person = {
  name: 'Jack',
  age: 34
}
console.log(person.age > 18 && 'Driving allowed');
// 'Driving allowed'

Since `person.age` is higher than 18, we get `true`. In this case, JavaScript has no `false` value, so the `&&` operator returns the last `true` value.

>To sum it up, for practical applications, we can use the `OR` operator to set default values, and we can use the `AND` operator to execute code in the second operand if the first one is true.

What are JavaScript short-circuiting operators?

Commonly, logical operators are used to combine two boolean values. But the truth is that we can do a lot more with the AND and OR operators.  In JavaScript, short-circuiting is the evaluation of an expression from left to right with  || and && operators.   If the condition is met and the rest of the conditions won t affect the already evaluated result, the expression will short-circuit and return that result (value).  