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TechCodex to Programmer [email protected]English • 2 years ago

Javascript can create atomic bombs

programming.dev

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Javascript can create atomic bombs

programming.dev

TechCodex to Programmer [email protected]English • 2 years ago
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  • @[email protected]
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    2 years ago

    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

    • @[email protected]
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      1•2 years ago

      wow that seems super useful, thanks

    • Rikudou_Sage
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      1•2 years ago

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

      • @[email protected]
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        1•2 years ago

        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

        • Rikudou_Sage
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          1•2 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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