zacechola/coercion-is-fun.md

Created May 12, 2015 20:30

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JavaScript is logical

Raw

[1] + [6] * [2] == 112 // true

Because:

[6] * [2] coerces to "6" * "2", which further coerces to 6 * 2, which equals 12.

[1] + 12 coerces to "1" + 12, which changes the meaning of "+" to concatenate, so the string "1" is concatenated to number 12, resulting in the string "112".

"112" == 112 makes a whole lot of sense now, doesn't it?

Author

zacechola commented May 13, 2015

I should note here that the reason [6] * [2] evaluates first is because of operator precedent.

As you know, 1 + 6 * 2 is equal to 13 and not 14, because multiplication is evaluated before addition.

Presumably, most people who complain about implicit coercion in JavaScript would prefer left-to-right evaluation, because math is hard. Or something.