• joneskind@lemmy.world
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    6 months ago

    in javascript a property is truthy if it exists

    myThing.property = "some string"
    
    if (myThing.property) { // true
      // do something
    }
    

    It works with everything except of course for falsy values

    myThing.number = someNumberThatShouldNotBeEqualToZero
    
    if (myThing.number) {
      // do something very important with that number that should not be equal to zero
    }
    
    // This can fail at anytime without warning
    

    So you’ve got to be extra careful with that logic when you’re dealing with numbers.

    I am not saying it’s wrong though. I’m saying it’s often annoying.

    • Skullgrid@lemmy.world
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      6 months ago

      ah ok , I think I write this a bit more verbose when using other languages, instead of

      if(thing)
      {
         stuff;
      }
      
      

      I do

      
      if(thing != null)
      {
         stuff;
      }
      

      so checking for numbers being truthy & existing didn’t seem like an issue

      • joneskind@lemmy.world
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        6 months ago

        In the case of a non-existing property, the value would be undefined rather than null.

        And while == and != exist in JavaScript, most linters will throw an error and require a === and !== instead as they should be avoided.

        null == undefined // true
        null === undefined // false
        

        Besides, null is a perfectly valid value for a property, just as 0. Working with API Platform, I couldn’t tell the number of times I used this kind of statement:

        if (property || property === null) {
          // do some stuff
        }
        

        Probably just as much as

        if (property || property === 0) {
          // do some stuff
        }