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 .

Answer 1

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); } 

Answer 2

You want hasOwnProperty():

var myObj1 = {   	prop1: 'no',  	prop2: function () { return false; }  }  var myObj2 = {   	prop1: 'no'  }    console.log(myObj1.hasOwnProperty('prop2')); // returns true  console.log(myObj2.hasOwnProperty('prop2')); // returns false  	

References: Mozilla, Microsoft, phrogz.net.