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Javascript can create atomic bombs (programming.dev)
submitted 3 years ago by to c/programmerhumor@lemmy.ml
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[–] 3 points 3 years ago* (last edited 3 years ago) (2 children)

2 equal signs will coerce the second operand into the type of first operand then do a comparison of it can. so 1 == "1" is true. this leads to strange bugs.

3 equal signs do not do implicit type conversion, cuts down on weird bugs. 1==="1" is false.

edit: it appears to be more complicated than that for double equals and the position of operands don't matter. https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Equality

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  • [–] 1 point 3 years ago (1 child)

    Doesn't it widen the types regardless of position? Meaning 1 == "1" will be compared as strings, not numbers.

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  • [–] 1 point 3 years ago (1 child)

    https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Equality

    mdn goes into it more and it's way more involved than I thought, looks like order of operand doesn't matter. see the number to string section

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  • [–] 1 point 3 years ago

    It seems it is that way, which is weird. You should always convert to the widest type, meaning string for comparing numbers and strings. I just checked that 1 == "01" is true, which means that "01" gets cast to an integer. And according to the document it might be that for example 1 == "a" would basically be interpreted as 1 === NaN which is false.

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