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Merge pull request #30 from aadithpm/patch-3

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Edit typos in article.md
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Ilya Kantor 2017-06-11 21:27:29 +03:00 • committed by GitHub
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1-js/02-first-steps/08-comparison/article.md
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@ -178,7 +178,7 @@ Yeah, mathematically that's strange. The last result states that "`null` is equa
The reason is that an equality check `==` and comparisons `> < >= <=` work differently. Comparisons convert `null` to a number, hence treat it as `0`. That's why (3) `null >= 0` is true and (1) `null > 0` is false. The reason is that an equality check `==` and comparisons `> < >= <=` work differently. Comparisons convert `null` to a number, hence treat it as `0`. That's why (3) `null >= 0` is true and (1) `null > 0` is false.
From the other hand, the equality check `==` for `undefined` and `null` works by the rule, without any conversions. They equal each other and don't equal anything else. That's why (2) `null == 0` is false. On the other hand, the equality check `==` for `undefined` and `null` works by the rule, without any conversions. They equal each other and don't equal anything else. That's why (2) `null == 0` is false.
### An incomparable undefined ### An incomparable undefined
@ -192,7 +192,7 @@ alert( undefined == 0 ); // false (3)
Why does it dislike a zero so much? Always false! Why does it dislike a zero so much? Always false!
We've got such result, because: We've got these results because:
- Comparisons `(1)` and `(2)` return `false` because `undefined` gets converted to `NaN`. And `NaN` is a special numeric value which returns `false` for all comparisons. - Comparisons `(1)` and `(2)` return `false` because `undefined` gets converted to `NaN`. And `NaN` is a special numeric value which returns `false` for all comparisons.
- The equality check `(3)` returns `false`, because `undefined` only equals `null` and no other value. - The equality check `(3)` returns `false`, because `undefined` only equals `null` and no other value.
@ -201,7 +201,7 @@ We've got such result, because:
Why did we observe these examples? Should we remember these pecularities all the time? Well, not really. Actually, these tricky things will gradually become familiar over the time, but there's a solid way to evade any problems with them. Why did we observe these examples? Should we remember these pecularities all the time? Well, not really. Actually, these tricky things will gradually become familiar over the time, but there's a solid way to evade any problems with them.
Just treat any comparison with `undefined/null` except the strict equality `===` with an exceptional care. Just treat any comparison with `undefined/null` except the strict equality `===` with exceptional care.
Don't use comparisons `>= > < <=` with a variable which may be `null/undefined`, unless you are really sure what you're doing. If a variable can have such values, then check for them separately. Don't use comparisons `>= > < <=` with a variable which may be `null/undefined`, unless you are really sure what you're doing. If a variable can have such values, then check for them separately.