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Merge pull request #217 from Thespawnexe/patch-4

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Moar spaces in 07-operators.
This commit is contained in:
Ilya Kantor 2017-09-27 15:16:28 +03:00 • committed by GitHub
commit 43c197889e
1 changed files with 6 additions and 6 deletions
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12
1-js/02-first-steps/07-operators/article.md
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@ -381,8 +381,8 @@ This notation can be shortened using operators `+=` and `*=`:
```js run
let n = 2;
n += 5; // now n=7 (same as n = n + 5)
n *= 2; // now n=14 (same as n = n * 2)
n += 5; // now n = 7 (same as n = n + 5)
n *= 2; // now n = 14 (same as n = n * 2)
alert( n ); // 14
```
@ -409,18 +409,18 @@ For example:
```js run
*!*
let a = (1+2, 3+4);
let a = (1 + 2, 3 + 4);
*/!*
alert( a ); // 7 (the result of 3+4)
alert( a ); // 7 (the result of 3 + 4)
```
Here, the first expression `1+2` is evaluated, and its result is thrown away, then `3+4` is evaluated and returned as the result.
Here, the first expression `1 + 2` is evaluated, and its result is thrown away, then `3 + 4` is evaluated and returned as the result.
```smart header="Comma has a very low precedence"
Please note that the comma operator has very low precedence, lower than `=`, so parentheses are important in the example above.
Without them: `a=1+2,3+4` evaluates `+` first, summing the numbers into `a=3,7`, then the assignment operator `=` assigns `a=3`, and then the number after the comma `7` is not processed anyhow, so it's ignored.
Without them: `a = 1 + 2, 3 + 4` evaluates `+` first, summing the numbers into `a = 3, 7`, then the assignment operator `=` assigns `a = 3`, and then the number after the comma `7` is not processed anyhow, so it's ignored.
```
Why do we need such an operator which throws away everything except the last part?