How to check if anonymous object has a method?

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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 .

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);

How to check if an object has a property properly in javascript, Use hasOwnProperty method. Use in keyword. Comparison with typeof. Check if the type of a property is undefined, is one of the most common  In anonymous methods, you are allowed to remove parameter-list, which means you can convert an anonymous method into a delegate. The anonymous-method-block means the scope of the parameters in the anonymous method. An anonymous method does not contain jump statements like goto, break, or continue. An anonymous method does not access unsafe code.

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

The Most Common Patterns To Create Objects In JavaScript, In the previous tutorial, you have learned how to create JavaScript objects The Animal() function has the prototype property pointing to the anonymous For more information on the prototype, check it out the JavaScript prototype tutorial. Yes, we can use a method on an object without assigning it to any reference. exampleLive Demopublic class Tester { public String message(){ ret

3 Options
  1. typeof myObj.prop2 === 'function' if the property name is not dynamic/generated
  2. myObj.hasOwnProperty('prop2') if the property name is dynamic, and only check if it is direct property (not down the prototype chain)
  3. 'prop2' in myObj if the property name is dynamic, and check down the prototype chain

Sleep 2.1 Manual, Use the isEmptyScalar method to test if a scalar is null or not. ProxyInterface class has several methods for generating an anonymous object that implements​  You can check whether the 'object' is such an object, provided by the .NET framework just in the same way – Frederik Gheysels Feb 25 '11 at 10:09 for example, you want to check whether there is an "Add" method in an object.

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

Modular Programming Languages: Joint Modular Languages Conference, , All that needs be done is to add the following method to the Matrix class: Iter rows​() () returns an anonymous object if (++x >= data. length) break; return Mutablelter In the following example we assume that the class tree has a method allEle- ments which returns an iterator and a method isLeaf to check if a tree is a leaf. This works for anonymous types, ExpandoObject, Nancy.DynamicDictionary or anything else that can be cast to IDictionary<string, object>. public static bool PropertyExists(dynamic obj, string name) { if (obj == null) return false; if (obj is IDictionary<string, object> dict) { return dict.ContainsKey(name); } return obj.GetType().GetProperty(name) != null; }

One way to do it must be if (typeof myObj.prop1 != "undefined") {...}, A Function object's read-only name property indicates the function's name as anonymous or ''(an empty string) for functions created anonymously. doesn't change function names, or don't assume a function to have a particular name. You can use to check the "class" of an object  Anonymous types typically are used in the select clause of a query expression to return a subset of the properties from each object in the source sequence. For more information about queries, see LINQ in C#. Anonymous types contain one or more public read-only properties. No other kinds of class members, such as methods or events, are valid.

Beginning ASP.NET Web Pages with WebMatrix, It contains a form, with server-side validation using the Validation Helpers and Internally, the method will examine your anonymous object and attempt to match based on the property names, so it is vital that you double check your spelling  How do I check if a property exists on a dynamic anonymous type in c#? (6) I have an anonymous type object that I receive as a dynamic from a method I would like to check in a property exists on that object.

Methods to determine if an Object has a given property, There are multiple ways to detect whether an Object has a property. You'd think it'​d be as easy as myObject.hasOwnProperty('prop'); - but no,  * Whenever an object is instantiated but is not assigned a reference variable, it is called anonymous object instantiation. Simple object instantiation: Sample s = new Sample(); Anonymous object instantiation: new Sample();

J2EE and Beyond, The second parameter to this method must be an object that implements the as the previous example, but in this case we create an anonymous object as a method can be used to check whether or not a permission has been granted to our  Dealing with anonymous type within a function was easy and a great aid while programming but when it came to passing them outside a function, it was too tough. Earlier (before C#4.0), it was very difficult to pass these Types among Method calls.

  • There's not much difference between anonymous and non-anonymous objects in JavaScript. They are the same under the cover.
  • try this if you want to check with dynamic variable if(typeof myObj[propoeryStr] === 'function') { ... }
  • this will not work if you have placed a dom node within a self-made object, eg if var my_obj = {'node1': document.createElement('div')}; then my_obj.node1.hasOwnProperty('cloneNode') is false. however Sean's solution will correctly return true: typeof my_obj.node1.cloneNode === 'function'
  • Won't work if you are looking for a method that was defined in the prototype.
  • @Wilt question specified anonymous object literal.
  • @artlung Yes your answer is good for the question, just wanted to leave that comment here for others who might be looking for similar a solution working in other cases (like me)... Didn't mean to disqualify your answer.
  • Doesn't handle the case where the property is defined, but is not a function.