If you have never heard of Operator Precedence and Associativity, or if you never truly understood that concept, that article is made for you !

In algebra, you all know that multiplication and division have a **higher precedence** than addition and subtraction.

With the expression **1 + 2 * 3**, you must first multiply **2 * 3** and then add **1** to the result.

Well, in **Javascript**, this concept is also **valid**, it is simply called **Operator Precedence**.

## Example

Precedence range from 1 to 19 :

- Multiplication has a precedence of
**13**. - Addition has a precedence of
**12**. - Grouping (putting the expression between parenthesis) has
**the highest precedence**. (19)

```
console.log(1 + 2 * 3);
// The multiplication is done first, the expression turns into
console.log(1 + 6)
// The addition is then evaluated, the result is 7
console.log((1 + 2) * 3);
// The grouped expression is read first, the expression turns into
console.log(3 * 3)
// The multiplication is then evaluated, the result is 9
```

The order of evaluation is also influenced by the **operator associativity**.

**Associativity** is the direction in which the expression is evaluated : **right to left** or **left to right**.

## Example

Assignment operators are **right-associative**, which means they are read from right to left :

```
a = b = 5
//is the same as
a = (b = 5)
```

## Exception

❗ Grouped expressions are **not always** read first.

If you use conditional evaluations, **the condition will be checked first**, then the expression between parenthesis will be evaluated.

```
a || (b * c);
//'a' is evaluated first, then (b * c) is evaluated if 'a' is false
a && (b < c);
//'a' is evaluated first, if 'a' is true (b * c) is evaluated
```

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