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fix precedence

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This commit is contained in:
Ilya Kantor 2018-07-17 11:59:02 +03:00
parent fab3cdbfef
commit dad2d807de
1 changed files with 5 additions and 7 deletions
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12
1-js/02-first-steps/11-logical-operators/article.md
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@ -230,14 +230,10 @@ When all values are truthy, the last value is returned:
alert( 1 && 2 && 3 ); // 3, the last one alert( 1 && 2 && 3 ); // 3, the last one
``` ```
````smart header="AND `&&` executes before OR `||`" ````smart header="Precedence of AND `&&` is higher than OR `||`"
The precedence of the AND `&&` operator is higher than OR `||`, so it executes before OR. The precedence of AND `&&` operator is higher than OR `||`.
In the code below `1 && 0` is calculated first: So the code `a && b || c && d` is essentially the same as if `&&` were in parentheses: `(a && b) || (c && d)`.
```js run
alert( 5 || 1 && 0 ); // 5
```
```` ````
Just like OR, the AND `&&` operator can sometimes replace `if`. Just like OR, the AND `&&` operator can sometimes replace `if`.
@ -303,3 +299,5 @@ There's a little more verbose way to do the same thing -- a built-in `Boolean` f
alert( Boolean("non-empty string") ); // true alert( Boolean("non-empty string") ); // true
alert( Boolean(null) ); // false alert( Boolean(null) ); // false
``` ```
The precedence of NOT `!` is the highest of all bitwise operators, so it always executes first, before any `&&`, `||`.