• activ8r@sh.itjust.works
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      1 year ago

      In JS a Boolean has 4 states.
      true
      false
      undefined (where the key is set to undefined)
      undefined (where the key doesn’t exist on the object)

      if (obj.value === true) {  
          console.log(1);
      } else if (obj.value === false) {
          console.log(2);
      } else if ("value" in obj) { // key "value" is in the obj, but it is set to undefined 
          console.log(3);
      } else { // key "value" is not in object
          console.log(4);
      }
      

      You’re welcome.