How to check if anonymous object has a method

Question

How can I check if an anonymous object that was created as such   var myObj          prop1   no       prop2  function      return false        does indeed have a prop2 defined   prop2 will always be defined as a function  but for some objects it is not required and will not be defined   I tried what was suggested here  How to determine if Native JavaScript Object has a Property Method  but I don t think it works for anonymous objects

User · Answer

What do you mean by an  anonymous object   myObj is not anonymous since you ve assigned an object literal to a variable  You can just test this   if  typeof myObj prop2      function            do whatever

User · Answer

3 Options   typeof myObj prop2      function  if the property name is not dynamic generated myObj hasOwnProperty  prop2   if the property name is dynamic  and only check if it is direct property  not down the prototype chain   prop2  in myObj if the property name is dynamic  and check down the prototype chain

User · Answer

One way to do it must be if  typeof myObj prop1     undefined

User · Answer

You want hasOwnProperty      x000D   x000D  var myObj1      x000D   prop1   no   x000D   prop2  function      return false    x000D    x000D  var myObj2      x000D   prop1   no  x000D    x000D   x000D  console log myObj1 hasOwnProperty  prop2        returns true x000D  console log myObj2 hasOwnProperty  prop2        returns false x000D    x000D   x000D   x000D    References  Mozilla  Microsoft  phrogz net

User · Answer

I know this is an old question  but I am surprised that all answers ensure that the method exists and it is a function  when the OP does only want to check for existence  To know it is a function  as many have stated  you may use   typeof myObj prop2      function    But you may also use as a condition   typeof myObj prop2   Or even   myObj prop2   This is so because a function evaluates to true and undefined evaluates to false  So if you know that if the member exists it may only be a function  you can use   if myObj prop2       lt we have prop2 gt      Or in an expression   myObj prop2    lt exists computation gt     lt no prop2 computation gt

User · Answer

typeof myObj prop2      function   will let you know if the function is defined   if typeof myObj prop2      function         alert  It s a function      else if  typeof myObj prop2      undefined         alert  It s undefined      else       alert  It s neither undefined nor a function  It s a     typeof myObj prop2

[javascript] How to check if anonymous object has a method?

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