Commit d512818

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minor fixes

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Lines changed: 5 additions & 3 deletions

Original file line number	Diff line number	Diff line change
`@@ -46,13 +46,15 @@ Besides regular numbers, there are so-called "special numeric values" which also`
`46`	`46`	`alert( "not a number" / 2 ); // NaN, such division is erroneous`
`47`	`47`	```
`48`	`48`
`49`		- `NaN` is sticky. Any further operation on `NaN` returns `NaN`:
	`49`	+ `NaN` is sticky. Any further mathematical operation on `NaN` returns `NaN`:
`50`	`50`
`51`	`51`	```js run
`52`		`- alert( "not a number" / 2 + 5 ); // NaN`
	`52`	`+ alert( NaN + 1 ); // NaN`
	`53`	`+ alert( 3 * NaN ); // NaN`
	`54`	`+ alert( "not a number" / 2 - 1 ); // NaN`
`53`	`55`	```
`54`	`56`
`55`		- So, if there's a `NaN` somewhere in a mathematical expression, it propagates to the whole result.
	`57`	+ So, if there's a `NaN` somewhere in a mathematical expression, it propagates to the whole result (there's only one exception to that:`NaN ** 0` is `1`).
`56`	`58`
`57`	`59`	```smart header="Mathematical operations are safe"
`58`	`60`	`Doing maths is "safe" in JavaScript. We can do anything: divide by zero, treat non-numeric strings as numbers, etc.`

Lines changed: 4 additions & 0 deletions

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`@@ -59,6 +59,10 @@ alert( str.match(/\d+\b(?!€)/g) ); // 2 (the price is not matched)`
`59`	`59`
`60`	`60`	`## Lookbehind`
`61`	`61`
	`62`	+```warn header="Lookbehind browser compatibility"
	`63`	`+Please Note: Lookbehind is not supported in non-V8 browsers, such as Safari, Internet Explorer.`
	`64`	+```
	`65`	`+`
`62`	`66`	`Lookahead allows to add a condition for "what follows".`
`63`	`67`
`64`	`68`	`Lookbehind is similar, but it looks behind. That is, it allows to match a pattern only if there's something before it.`

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