Is there a not in operator in JavaScript for checking object properties

Question

Is there any sort of  not in  operator in JavaScript to check if a property does not exist in an object  I couldn   t find anything about this around Google or Stack Overflow  Here   s a small snippet of code I   m working on where I need this kind of functionality   var tutorTimes          checked  each function idx     id     this  attr  class       if id in tutorTimes      else        Rest of my logic will go here           As you can see  I   d be putting everything into the else statement  It seems wrong to me to set up an if   else statement just to use the else portion

User · Answer

Personally I find   if  id in tutorTimes     false            easier to read than   if    id in tutorTimes             but both will work

User · Answer

As already said by Jord  o  just negate it   if    id in tutorTimes             Note  The above test if tutorTimes has a property with the name specified in id  anywhere in the prototype chain  For example  valueOf  in tutorTimes returns true because it is defined in Object prototype   If you want to test if a property doesn t exist in the current object  use hasOwnProperty   if   tutorTimes hasOwnProperty id             Or if you might have a key that is hasOwnPropery you can use this   if   Object prototype hasOwnProperty call tutorTimes id

User · Answer

Two quick possibilities   if    foo  in myObj             or  if myObj  foo       undefined

User · Answer

It seems wrong to me to set up an if else statement just to use the else portion      Just negate your condition  and you ll get the else logic inside the if   if    id in tutorTimes

[javascript] Is there a “not in” operator in JavaScript for checking object properties?

Examples related to javascript

Examples related to object

Examples related to properties

Examples related to operators